StarDate Online - Your guide to the universe: Recent Episodes

A good home for future lunar colonists might be pit craters -- holes in the surface that are part of collapsed lava tubes. The tubes can extend a long way, providing protection from radiation, meteorites, and other hazards. These are three views of a pit crater in the Moon's Marius Hills, taken at different Sun angles. The pit is more than 100 feet deep, and is as wide as a football field. [NASA/GSFC/Arizona State]

The thin crescent Moon will stand low in the sky at dawn tomorrow, with a close, brilliant companion: Venus, the Morning Star. Earth’s closest planetary neighbor is the brightest object in the night sky other than the Moon.

When most of us move, we pick existing houses or apartments instead of building from scratch. And that could be an option for future explorers on the Moon. Scientists have identified some structures that could be entryways to roomy accommodations. They’re not secret bases built by aliens. Instead, they’re holes in the ground — “pit” craters that could link up with long, deep caves.

Living on the Moon would be dangerous. There’s no air, the temperatures range from extremely hot to extremely cold, and the surface is pelted by radiation and space rocks. A habitat inside a cave would offer protection from those hazards.

Scientists have identified almost 300 pit craters. Most of them link to underground tubes, which once carried molten lava. When the lava went away, parts of the tubes collapsed, forming the pits. But parts of the tubes remain intact, creating caves that could go on for miles.

A team recently picked out four pit craters that are especially interesting. Their caves could make good habitats for lunar explorers, and provide a lot of information about the Moon’s geologic history.

The leading candidate is in the Marius Hills, on the Moon’s Ocean of Storms. The others are in the Sea of Tranquility, Sea of Cleverness, and Lake of Death — possible addresses for lunar explorers.

The crescent Moon is low in the sky at dawn tomorrow. And it has a brilliant companion: Venus — the “morning star.”

Script by Damond Benningfield

Navy pilots took to the air 100 years ago today to view one of nature’s most amazing sights: a total solar eclipse. It was the first time that airplanes had been used to study an eclipse. In fact, it was the first attempt at airborne astronomy — studying the universe from above as much of the atmosphere as possible.

Most of the eclipse path was over the Pacific Ocean. But it clipped some islands in southwestern California, then continued across northern Mexico.

Astronomers from around the world set up bases to watch the eclipse — projects that involved years of preparation, dozens of people, and massive logistics efforts. But when the eclipse rolled around, most of them were stymied by clouds.

The U.S. Navy sent up 16 airplanes to watch the eclipse — biplanes with open cockpits. Their main goal was to plot the centerline of the eclipse. That would help astronomers refine their calculations of the Moon’s orbit. A second goal was to snap pictures of the Sun’s corona — its hot, thin outer atmosphere.

Pilots flew at altitudes of one to three miles, across California, Mexico, and the Pacific. They made important observations of the shadow, but none of their pictures worked out — the film was too slow, the airplanes too jittery, the skies too cloudy. But more successful eclipse flights would follow in the coming decades — watching cosmic spectacles from on high.
 

Script by Damond Benningfield

Dazzling Venus will stand to the lower right of the Moon at first light tomorrow. Although it’s described as the Morning Star, Venus is actually the second planet out from the Sun. It shines so brightly in part because its entire surface is blanketed by clouds.

Radio telescopes around the world are listening for the whispers of other civilizations. That includes the Very Large Array — a set of 27 radio dishes that acts as a single giant telescope.

The VLA is conducting a survey of most of the sky. And a few months ago, scientists who are hunting for civilizations in other star systems began tapping into that survey. They’re looking at narrow sets of frequencies that are the most likely to have an intelligent origin.

Scientists also are pondering whether other civilizations could hear us. We produce a constant radio “haze,” including the drone of billions of cell phone calls. And a team recently looked at whether any close-by civilization might be able to “eavesdrop” on those calls.

The team looked at the radio waves that leak into space from some of the most powerful cell-phone towers. It calculated whether that leakage could be picked up by Earth-like radio telescopes at three nearby star systems, including the two closest, Alpha Centauri and Barnard’s Star.

The team found that the signals fade away before they reach any of those stars — you’d need more advanced technology to hear them. But the team is extending its work to include other types of Earthly transmissions, including military radar, orbiting satellites, the network that talks to deep-space missions, and future cell towers. That should tell us whether Earth is loud enough to be heard by ET.
 

Script by Damond Benningfield

A pair of scientific satellites with widely differerent goals launches from Japan on September 7 (Japanese time). XRISM (X-Ray Imaging and Spectroscopic Mission) will study the universe at X-ray wavelengths. That will reveal details about black holes, exploding stars, and other powerful events. It also will examine the chemistry of the universe and the growth of galaxy clusters, which are the largest structures in the universe. Its companion, SLIM (Smart Lander for Investigating Moon), is a technology demonstrator that is designed to make a pinpoint lunar landing. It should enter lunar orbit around the end of the year, and land a month or two later. If successful, it would make Japan the fifth nation to land on the Moon, following the Soviet Union, United States, China, and India. [JAXA]

The North Star, Polaris, is often used as an icon of steadiness. But Polaris isn’t steady at all. Instead, it changes brightness, because it pulses in and out like a beating heart.

55 Cancri is a busy star system. It consists of two stars and at least five planets. None of the planets is a good home for life, although there could be undiscovered planets that are more welcoming.

The planets have a couple of sets of names. Their scientific designations are 55 Cancri b, c, d, e, and f. But a few years back, the IAU — the International Astronomical Union — gave them proper names: Galileo, Brahe, Lipperhey, Janssen, and Harriot. They’re named for astronomers, or for lensmakers involved in creating early telescopes.

Astronomers have discovered more than 5,000 planets in other star systems. And hundreds more are added to the list every year. That’s a lot of worlds to name.

The scientific designations take the name of the star — a proper name or a catalog name — and add a letter, starting with b. The letters are applied based on the order in which the planets were discovered.

The IAU has held several contests to pick proper names, and it’s adopted about 150 of the suggestions. They come from scores of countries and cultures — named for people, places, animals, and other sources. And if a system has more than one planet, a single theme is applied to all of the planets — like the planets of 55 Cancri.

The system is in the constellation Cancer, which is in the east at first light. The crab is easy to pick out because it spreads to the upper left of Venus, the “morning star.”
 

Script by Damond Benningfield

The system 55 Cancri consists of two stars and at least five planets. None of the planets is a good home for life, however. The system is in Cancer, which is in the east at first light. The crab is easy to pick out because it spreads to the upper left of Venus, the Morning Star.

The two brightest stars of Taurus, the bull, flank the Moon late tonight. The brighter of the two, Aldebaran, is off to the right of the Moon as they climb into good view, about 1 a.m. The second-brightest star, El Nath, is closer to the left or lower left of the Moon. And it’ll stand even closer to the Moon at first light.

Aldebaran and El Nath are in the same stage of life — they’re giants. Through nuclear fusion, each has burned through the original hydrogen fuel in its core, converting it to helium. Now, it’s burning the hydrogen in a thin shell around the core. At the same time, the core is getting smaller and hotter. Eventually, it’ll get so hot that fusion reactions will fire up in the helium, making the star even bigger and brighter.

Nuclear fusion combines lighter elements to make heavier ones. The process releases energy — a lot of it. The core of the Sun, for example, “fuses” 700 million tons of hydrogen every second, producing 695 million tons of helium. The other five million tons are converted to energy — and that’s what makes the Sun shine.

Even at that rate of consumption, the Sun has so much hydrogen in its core that it won’t run out any time soon. It’s been burning through the hydrogen for four and a half billion years, and it’ll keep doing so for at least five billion years longer — powered by its own giant nuclear reactor.

Tomorrow: naming the planets in other star systems.
 

Script by Damond Benningfield

The two brightest stars of Taurus, the bull, flank the Moon late tonight. The brighter of the two, Aldebaran, is to the right of the Moon as they climb into good view, about 1 a.m. The second-brightest star, El Nath, is closer to the left or lower left of the Moon.

Quite a few stars that are visible to the unaided eye are like previews of coming attractions: They show us what will happen to the Sun in several billion years.

Perhaps the prime example is Aldebaran, the bright orange eye of the bull. It rises below the Moon late tonight, and follows the Moon across the sky.

Aldebaran has moved past the prime of life, so the nuclear reactions in its core have settled into a new mode. That’s made the star puff up to become a giant. So even though it’s only a little more massive than the Sun, it’s more than 40 times wider, and hundreds of times brighter.

In another few hundred million years, Aldebaran’s nuclear reactions will shut down. Aldebaran will expel its outer layers into space, creating an expanding cloud of gas and dust. The tiny, dead core will be extremely hot. Its radiation will set the surrounding material aglow, creating a colorful planetary nebula. It’ll shine for tens of thousands of years, until its material gets too thinly spread.

The Sun will reach its giant phase in several billion years. It, too, will then kick its outer layers into space. Astronomers aren’t quite sure if its dead core will be hot and bright enough to light up that material. So the Sun might produce a planetary nebula, or it might die in obscurity — simply fading into the long cosmic night.

We’ll talk about the Moon and another bright star in the bull tomorrow.
 

Script by Damond Benningfield

Aldebaran, the bright orange eye of the bull, rises below the Moon late tonight, and follows the Moon across the sky. Aldebaran has puffed up, becoming a red giant. The Sun will enter that phase of life in several billion years.

The western evening sky offers a figure that seems just right for Labor Day: Hercules, the strongman. In mythology, he had to labor not once, but 12 times. If you have a dark sky, look for Hercules high in the west after nightfall.

The stars of the binary system SSN 7 are doomed, doomed, and doomed. Each of the two monster stars will collapse to form a black hole. And in the far-distant future, the black holes will merge to form a bigger one.

The system is about 200,000 light-years from Earth. It’s in a massive stellar nursery in the Small Magellanic Cloud, a companion galaxy to the Milky Way.

A recent study found that one star in the system is about 32 time the mass of the Sun, while the other is 55 times the Sun’s mass. That makes them some of the hottest, brightest, and heaviest stars in the universe. They’re only about four million years old — about one percent the age of the Sun. But because they’re so massive, they’re nearing the ends of their lives.

The study concluded that the stars are so close together that they’re touching each other. Not only that, but the heavier star is “stealing” hot gas from its companion. In as little as 700,000 years, the less-massive star will collapse to form a black hole. After a brief quiet period, it will begin pulling in gas from the surviving star, which will collapse as well. The entire scenario should play out in just a few million years.

After that, the black holes will spiral ever closer as they emit gravitational waves — “ripples” in space-time. The study forecasts that they’ll merge in about 18 billion years — several billion years longer than the current age of the universe.
 

Script by Damond Benningfield

By Jove, the Moon and the planet Jupiter put on a good show the next couple of nights. They climb into good view by about 11 or 11:30. Jupiter looks like a brilliant star near the Moon — only the Moon and the planet Venus outshine it.

Jupiter is named for a Roman god — the equivalent of Zeus, the king of the Greek gods. Appropriately enough, Jupiter was a sky god. And like Zeus, he was in charge of everything — the leader of all the gods. He was considered a protector of Rome, so military commanders visited one of his temples after a successful battle to give thanks.

Jupiter was also known as Jove. The name is used in the phrase “by Jove!”, which indicates surprise or adds emphasis. According to Miriam-Webster, the phrase was mainly British, and it’s been largely abandoned.

“Jove” is still a part of daily language, though, mainly in the word “jovial” — showing “good-humored cheerfulness.” Other forms of the word include “jovialize,” which means “to make jovial,” and “jovialist” — someone who’s already jovial.

Look for Jove — or Jupiter — rising in late evening, near the gibbous Moon. The solar system’s biggest planet is to the lower left of the Moon tonight, and about the same distance to the right of the Moon tomorrow night. By Jove, the view is pretty much guaranteed to make just about anyone feel jovial — jovialists under the stars.

Tomorrow: a pair of giant stars with a non-jovial future.
 

Script by Damond Benningfield

The Moon and the planet Jupiter put on a good show the next couple of nights. They climb into good view by about 11 or 11:30 p.m. Jupiter looks like a brilliant star near the Moon. Only the Moon and the planet Venus outshine it.

Millions of stars plus dark lanes of dust highlight this James Webb Space Telescope image of M51, the Whirlpool Galaxy. The image was snapped in infrared light and colors were assigned to different infrared wavelengths. The different colors represent different types of gas within the spiral galaxy, which is about 27 million light-years from Earth. [ESA-Webb/NASA/CSA/A. Adamo (Stockholm University)/FEAST JWST team]

Several “heartbeat” stars are in Cygnus. The swan’s brightest star, Deneb, is high in the east-northeast at nightfall. The heartbeat stars are binaries that follow elongated orbits. As a result, the systems brighten and dim in a way that resembles the pulse of a beating heart.

If that sounds like beating hearts, that’s because it is — in a way. It’s the sound of “heartbeat” stars. If you plot how the light from such a star changes, it looks like an EKG — like a beating heart. Scientists have converted some of those beats to sound, and sped them up to show the rhythm of the heartbeats.

The stars are actually binaries — pairs of stars locked in orbit around each other. Their orbits are stretched out — they’re long and thin. Depending on the system, each orbit takes a few days to a few weeks, so the system “beats” at up to a few times per month.

When the two stars are at their closest, the gravity of each star distorts the shape of the other, making the stars bulge toward each other. That creates more surface area for both stars, making the system brighter. At the same time, the surfaces of the stars vibrate like ringing bells. That also changes their brightness.

Astronomers have discovered about 1300 heartbeat systems. Most of them consist of stars that are bigger, brighter, and more massive than the Sun. Such stars are more likely to be born in pairs than Sun-like stars are.

Several heartbeat systems are in Cygnus. The swan’s brightest star, Deneb, is high in the east-northeast as night falls, and passes almost directly overhead later on — surrounded by stars that produce their own heartbeats.
 

Script by Damond Benningfield

Two points of the Summer Triangle crown the sky tonight. Depending on your latitude, they can pass at or quite close to the zenith, the point directly overhead. Vega is up first, in early evening, followed by Deneb a couple of hours later.

It looks like Roman calendar makers just ran out of gas. They named the first eight months of the year for gods and goddesses, or for emperors with godly ambitions. But after that, all they could come up with were numbers indicating a month’s position in the year.

September, for example, means “seventh month.” We know that Star Date listeners are pretty bright, so you’ve no doubt noticed that September is actually the ninth month of the year. But in the original Roman calendar, the year began in March, and lasted only 10 months. January and February were added later.

In other cultures, the calendar year began at different times. In Egypt, for example, it started in July, when Sirius returned to view in the morning sky.

Sirius is the brightest star in the night sky. Just as important to the Egyptians, it returned to view about the same time as the Nile’s annual life-giving floods. Using Sirius as a marker, the Egyptians established the first known 365-day calendar. Later, they added leap days to keep the calendar in sync with the seasons.

Much later, the Romans were fussing with a calendar that was a mess. Its months didn’t add up to a full year, so extra days or months were added at whim. So in 46 B.C., Julius Caesar ordered up a new calendar. Rome adopted the 365-and-a-quarter-day year — perhaps influenced by the Egyptian calendar. But it kept the Roman names for the months — including September.
 

Script by Damond Benningfield

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One of the most brilliant stars is a dominant presence from late spring through autumn. Vega is the fifth-brightest star in the night sky. It is about a third of the way up in the east-northeast at nightfall now, and climbs high overhead later on.

One of the most brilliant stars in the night sky is a dominant presence from late spring through autumn. Vega is the fifth-brightest star in all the night sky. It’s about a third of the way up in the east-northeast at nightfall now, and climbs high overhead later on.

Vega is just 25 light-years away — a close neighbor. That’s one reason it appears so bright. But it really is an impressive star. It’s more than twice as big and heavy as the Sun, and about 40 times brighter.

Vega is encircled by a disk of dust. Such disks can provide the raw materials for planets. Vega is already about 450 million years old, though, which is well beyond the expected planet-birthing years. So the disk isn’t likely to spawn any new planets.

But Vega might already have a planet.

Astronomers looked at a decade of observations of Vega. The observations ruled out many possible types of planets — including one that was hinted at in some earlier work. But they did suggest that a planet about 20 times the mass of Earth orbits Vega every two and a half days.

The discovery isn’t especially solid. But if the planet’s really there, it orbits Vega roughly around its poles, not around the equator, as Earth orbits the Sun. And it’s so close to Vega — a hot, bright star — that it would be one of the hottest planets yet seen: roughly 5400 degrees on its dayside — a broiling planet around a hot star.

More about super-hot planets tomorrow.
 

Script by Damond Benningfield

We’re sorry if it makes you feel a bit squeamish, but trillions of ghostly particles from beyond Earth zip through your body every second. Known as neutrinos, they’re not harmful, because they almost never interact with other matter. In fact, they can pass through an entire planet or even a star without so much as a wiggle.

That’s good for planets and stars, but not so good for astronomers. They want to study neutrinos because they’re produced in stars, exploding stars, and other powerful objects and events. So they can reveal details about what’s going on inside those objects. If neutrinos aren’t affected by other matter, though, it’s impossible to catch them. And if you can’t catch them, you can’t really study them.

Every once in a while, though, a neutrino does cause a reaction from another bit of matter — a faint flash of light.

And 25 years ago today, scientists announced something new revealed by the flashes: neutrinos have mass. Before that discovery, it was thought that neutrinos had no mass at all.

It was known that neutrinos come in three varieties, called flavors. Using a detector buried far beneath a Japanese mountain, the scientists found that some neutrinos can change flavor. The only way that could happen is if neutrinos have mass.

The mass is tiny. Still, there are so many neutrinos that it adds up — a bit of substance from some ghostly particles.
 

Script by Damond Benningfield

The year’s earliest sunrises in the northern hemisphere occur over the next few days. The date varies by latitude, with southern locations getting that extra sunlight first. The longest day of the year is the summer solstice, June 21.

The Moon is just a day past full tonight, so it overpowers the fainter stars. But some bright stars shine through. Among them are the points of the Summer Triangle, Vega, Deneb, and Altair, which are in the east and northeast as twilight fades.

Visitors to the Grand Canyon will find a bonus beginning on Saturday: the Grand Canyon Star Party. The week-long party will offer tours of the night sky, telescope viewing, and other events on both the north and south rims. And the only cost is the usual park entry fee.

If you can’t make it, though, don’t worry — there are plenty of star parties to go around — from California to Maine, Washington to Florida. COVID-19 wiped out many events in 2020 and beyond. But most of them are back this summer.

Some will be held in national parks, such as Grand Canyon and Bryce Canyon, in Utah, which offer especially dark skies. Others are hosted by private groups, although they, too, seek out parks and other locations far from city lights. The big parties last for days, with many attendees camping on site.

Many other groups, such as museums and observatories, offer shorter events — a night here and there. Some are free, some are not. But most offer nice views of the night sky for novices and veterans alike.

Of course, we’re partial to the star parties at McDonald Observatory. During the summer months, they’re generally offered four nights a week, beginning about the time the sky gets good and dark. Experts provide naked-eye tours of the stars under some of the darkest skies in North America. And several telescopes offer up-close views of galaxies, nebulas, planets, and other astronomical wonders — at parties that celebrate the beauty of the universe. You can find details at mcdonaldobervatory.org.
 

Script by Damond Benningfield

Antares, the heart of the scorpion, is close to the full Moon tonight. Antares is one of the most colorful stars in the night sky, shining reddish orange. The color indicates that its surface temperature is much lower than the temperature of the yellow Sun.

The 200-inch Hale Telescope peers out from its massive dome, with the Pleiades star cluster and the bright star Aldebaran in the background. The telescope, at Palomar Observatory in southern California, was dedicated 75 years ago, and was the largest in the world for almost three decades. It's still an astronomical workhorse, gazing at the cosmos every clear night of the year. [Damond Benningfield]

Giant new telescopes pop up like mushrooms these days — there’s another one every year or two. And even bigger ones are on the way.

But one telescope reigned supreme for almost three decades: the 200-inch at Palomar Observatory in southern California. It was dedicated 75 years ago today. At the ceremony, the president of Caltech, which operated the telescope, announced that it was being named for a pioneering astronomer...

LEE DUBRIDGE: George Ellery Hale, who served as director of the Mount Wilson Observatory from 1904 to 1923, who originated the bold conception of the 200-inch telescope, and whose brilliant leadership made possible its design and construction.

Hale had founded Yerkes Observatory in Wisconsin, then moved to the clearer skies of California, where he founded Mount Wilson and built its 100-inch telescope — the largest in the world until the 200-inch came along. He also established a lab for studying the Sun.

Hale kept pushing for bigger telescopes and better instruments, and got the funding for the 200-inch in the 1930s. Development problems and World War II delayed its completion until 1948 — a decade after Hale died.

Since then, the telescope has made major contributions to every field of astronomy, from the planets of the solar system to distant galaxies and quasars. And although it’s no longer the world’s largest — it’s barely in the top 20 — it’s still busy every clear night, keeping a giant “eye” on the stars.
 

Script by Damond Benningfield

The Moon will be full tomorrow night. It’s the Flower Moon, Rose Moon, or Strawberry Moon. But it also can be called the Short-Night Moon. It puts in one of the shortest appearances of any full Moon of the year. Only July’s Moon will surpass its brevity, although not by much.

The Moon will be full tomorrow night. It’s the Flower Moon, Rose Moon, or Strawberry Moon. But it can also be called the Short Moon or Short-Night Moon. It puts in one of the shortest appearances of any full Moon of the year. Only July’s Moon will surpass its brevity — but not by much.

These Moons are so bashful because the full Moon does the opposite of what the Sun is doing in our sky. These are the longest days of the year in the northern hemisphere, so the Sun remains in view for a long time. It also stands highest in the sky for the year.

So the full Moon does just the opposite: It stays fairly low, and with the shortest nights of the year upon us, it’s in view for only a few hours.

The difference is more pronounced as you go farther north. Miami, for example, sees about 13 and a half hours of sunlight the next few days, but as little as 10 and half hours of moonlight. From Dallas, it’s more than 14 hours of the Sun, but only 10 hours of the Moon. And from Seattle, it’s 16 hours versus just eight.

The Short Moon is the full Moon closest to the summer solstice, which is June 21st — 18 days after tomorrow night’s full Moon. July’s full Moon comes on the 3rd — 11 days after the solstice. It’ll be in view for a few minutes less than June’s Moon. So, technically, it earns the Short Moon tag. But both full Moons will be so scarce that they might as well share this year’s honors: the Short-Night Moon.
 

Script by Damond Benningfield

The planet Mars will pass directly across M44, the Beehive Cluster, over the next couple of nights. They are a third of the way up the western sky at nightfall, to the upper left of Venus, the Evening Star. Mars looks like a fairly bright orange star.

Mars and Venus will pass near a star cluster with many aliases this month. It’s probably best known as the Beehive. But it’s also known as Praesepe — Latin for “crib” or “manger” — as well as Messier 44 and NGC 2632. Astronomers have many other names for it, most of which are long catalog numbers.

The cluster is in Cancer, the crab. From a distance of at least 600 light-years, it looks like a hazy smudge of light. Binoculars reveal there’s more to it — a swarm of stars that looks like bees buzzing around their hive.

Astronomers have identified about a thousand members of the cluster. A few are bigger and brighter than the Sun, and congregate in the cluster’s middle.

But most of the bees are much fainter and smaller than the Sun. They spread up to a few dozen light-years from the core. Those stars won’t hang around forever, though. They’re being tugged by the gravity of the galaxy’s other stars and gas clouds. Eventually, they’ll be stripped away and head off on their own.

Mars will pass directly across the cluster over the next couple of nights. They’re a third of the way up the western sky at nightfall, to the upper left of Venus, the “evening star.” Mars looks like a fairly bright orange star.

Mars will move away from the cluster after tomorrow night, with Venus closing in on it night by night. Venus will be closest on the 12th — an encounter with a star cluster with lots of aliases.
 

Script by Damond Benningfield

The Moon is passing through the constellation Virgo tonight, with its leading light, Spica, close to the Moon’s upper right. A beautiful galaxy, the Sombrero, is about the same distance to the lower right of Spica. It’s an easy target for telescopes.

The Sombrero Galaxy has taught us a lot. It provided important details about the birth, scale, and evolution of the universe. And it’s a good laboratory for studying the birth of stars and the feeding habits of giant black holes.

The Sombrero is about 30 million light-years away. It forms a disk that we see almost edge-on. It has a bright “bulge” of stars in the middle, and a lane of dark dust around its rim. That makes it look like a sombrero.

In 1912, V.M. Slipher discovered that the galaxy is moving away from us at about 25 million miles per hour. At the time, astronomers were debating whether the entire universe was contained inside the Milky Way. Slipher’s discovery indicated that the Sombrero was a separate galaxy, far beyond the Milky Way. It also suggested that the universe was expanding.

The galaxy has a central black hole that’s roughly 250 times the mass of the Milky Way’s black hole. It appears to be “feeding” on massive amounts of gas, perhaps funneled in from outside the galaxy.

Stars are being born in the galaxy’s ring of dust. Studying that process can tell astronomers more about how stars are born — all from the “brim” of a galactic sombrero.

The Sombrero is in Virgo. The Moon is passing through the constellation tonight, with Virgo’s leading light, Spica, close to its upper right. The Sombrero is about the same distance to the lower right of Spica, and is an easy target for telescopes.
 

Script by Damond Benningfield

A dark lane of dust outlines the disk of Messier 104, giving the galaxy a festive nickname: the Sombrero. The galaxy is about 30 million light-years away, in Virgo. It has a bright “bulge” of stars in the middle, and a lane of dark dust around its rim. The galaxy has a central black hole that’s roughly 250 times the mass of the Milky Way’s black hole. It appears to be “feeding” on massive amounts of gas, perhaps funneled in from outside the galaxy. Stars are being born in a ring of dust along the dark rim.
[ESO/IDA/Danish 1.5 m/R. Gendler and J.-E. Ovaldsen]

The Moon stands near the middle of the largest member of the zodiac tonight, the constellation Virgo. Spica, its brightest star, is close to the Moon at nightfall, and the Moon will slide even closer to it during the night.

The Moon stands near the middle of the largest member of the zodiac tonight, the constellation Virgo. Spica, the maiden’s brightest star, is close to the Moon as darkness falls, and the Moon will slide a little closer to it during the night. Spica represents an ear of wheat held in the maiden’s hand.

Virgo is the second largest of all the modern constellations. Only Hydra, the water snake, outranks it. But it’s not the size of the constellation that’s made it one of the most important. Instead, it’s the fact that the Sun passes through its borders at the time of the September equinox — the beginning of autumn in the northern hemisphere.

Because of Virgo’s great size, the Sun spends a long time inside its borders — more than seven weeks — from mid-September until the end of October. That’s longer than it stays inside any other constellation.

But the Sun hasn’t always been passing through Virgo at the equinox. Until about the year 730 B.C., it was in the adjoining constellation Libra.

The change is due to precession — a slow “wobble” of Earth’s axis. It takes about 26,000 years to complete one wobble. During that time, the Sun glides through the background of stars. That means the point of the equinox changes as well. It’ll shift over into Leo in about 400 years. And it’ll return to Virgo about 23,000 years after that — returning to the largest constellation of the zodiac.
 

Script by Damond Benningfield

Mars is moving at a leisurely pace — slower than at any other time during its almost two-year orbit around the Sun. That’s because it’s farthest from the Sun — 13 million miles farther than average. So the planet is coasting at about 50,000 miles per hour — thousands of miles per hour slower than its average speed.

Neither Mars nor any other planet follows a circular path around the Sun. Instead, their orbits are elliptical — they’re stretched out. And the orbit of Mars is more stretched than most. Its distance from the Sun varies by almost 10 percent in either direction.

Those details were worked out four centuries ago, by Johannes Kepler. At the time, astronomers assumed that the planets all followed circular orbits — perfect shapes. But Mars’s motion didn’t fit that idea.

Kepler pored through years of observations, mostly by his boss, Tycho Brahe. He then spent more years analyzing those observations. From that, he developed several laws of planetary motion. The first law says that Mars and the other planets follow elliptical paths. The second says that a planet moves faster when it’s close to the Sun, and slower when it’s farther away. Since Mars is at its maximum distance today, it’s moving at its slowest — a leisurely pace for the Red Planet.

Mars is a third of the way up the western sky at sunset, and looks like a fairly bright orange star. It’s to the upper left of Venus, the brilliant “evening star.”
 

Script by Damond Benningfield

Mars is a third of the way up the western sky at sunset and looks like a fairly bright orange star. It’s to the upper left of Venus, the brilliant Evening Star, by a little more than the width of your fist held at arm’s length.

Archaeologists recently released pictures of a hidden chamber inside the pyramid of Khufu, the largest of the Great Pyramids of Giza. The chamber was discovered with cosmic “X-rays.”

Cosmic rays are particles from exploding stars and other powerful events. When they strike atoms and molecules in Earth’s atmosphere, they create showers of other particles, including muons. They zip through solid matter — including the pyramid, which was built more than 4500 years ago. Detectors placed around the pyramid picked up the muons, providing a 3D view of its interior — revealing the 30-foot-long chamber.

The X-rays aren’t the pyramid’s only connection to the stars. It was laid out with the help of the North Star. And a shaft inside the pyramid points to another star.

When the pyramids were built, north was marked not by today’s North Star, Polaris, but by Thuban, a star in Draco. Under dark skies, it’s visible along the line between Polaris and the tip of the handle of the Big Dipper. The change is the result of a wobble in Earth’s axis. Guided by Thuban, architects aligned the pyramid with the cardinal directions with amazing precision.

The pyramid also contains a shaft that aims at Orion’s Belt. In ancient Egypt, the stars of Orion represented Osiris, the god of the underworld. A dead king joined Osiris as one of the stars in that part of the sky. So the shaft provided a path from this world to the next.
 

Script by Damond Benningfield

The Great Pyramid of Khufu, the largest of the pyramids of Giza, was aligned with the help of Thuban, the North Star at the time of its construction. And the pyramid contains a shaft that aims at Orion’s Belt, which represented the destination for the dead king.

Alphecca, the brightest star of Corona Borealis, the northern crown, is in a pretty semicircle of stars that’s high in the east at sunset, and passes across the top of the sky around midnight. Alphecca is at the middle of the semicircle.

Our solar system is heading into the aftermath of a stellar breakup — a ribbon of stars that split away from a big family of stars. One of the brightest members of the ribbon stands high overhead at midnight: Alphecca, the brightest star of Corona Borealis, the northern crown.

The stars in the ribbon were once members of a good-sized cluster. Today, though, the cluster’s been whittled down to only about a dozen stars, including five stars of the Big Dipper.

The cluster is being torn apart by the gravitational tug of other stars, plus giant clouds of gas and dust. Dozens of stars that once belonged to the cluster are now moving through the galaxy on their own. They form a ribbon that spans hundreds of light-years. The Sun is on the outskirts of the ribbon, but it’s moving in a different direction.

Astronomers are pretty sure of the origin of the stars in the stream because they still move in the same speed and direction as the cluster’s core. The stars are all about the same age, too. And they have the same chemical composition — good indications that they’re all members of the same stellar family.

Alphecca is 75 light-years away — about the same distance as the cluster’s core. It’s in a pretty semicircle of stars that’s high in the east at sunset, and passes across the top of the sky around midnight. Alphecca is at the middle of the semicircle — a member of a big stellar family that’s heading off on its own.
 

Script by Damond Benningfield

Dark sunspots highlight this mosaic of newly released images from the Daniel K. Inouye Solar Telescope in Hawaii, which is still in its commissioning phase. The sunspots, which can be as big as Earth or larger, are magnetic storms that are thousands of degrees cooler than the surrounding gas. They're often associated with eruptions of energy and particles that race into the solar system. A few of the images show quieter regions of the Sun, with bubbles of hot gas on its surface as big as the state of New Mexico. The telescope is the largest solar telescope in the world, providing the sharpest ground-based observations of the Sun to date. [National Solar Observatory/AURA/NSF]

The bright heart of the lion beats near the Moon this evening. Regulus, the star that marks the heart of Leo, stands quite close to the lower left of the Moon at nightfall.

And Regulus is a strong heart. It’s much bigger, brighter, and more massive than the Sun. And it spins about 15 times faster — more than 700,000 miles per hour at the equator.

Regulus whirls around so fast because it “stole” a lot of gas from a nearby companion star. As the gas poured in, Regulus twirled faster and faster. Today, it spins so fast that it bulges outward at the equator, so it looks like a smashed beachball.

If Regulus were to spin just 10 percent faster, it would rip itself apart. That’s unlikely to happen — for one thing, it’s already pulled in all of the available gas from its companion.

But some other stars are seen to spin much closer to that edge. Gas squirts away from such a star’s equator, forming a disk around it.

As the gas moves out, it can come together to form tiny grains of dust. The stardust absorbs some of the star’s light — especially blue light. That can make the star look much redder than it really is. In the 1800s, for example, astronomer John Russell Hind watched as one star changed from red to blue in a matter of weeks. The most likely explanation is that the star had spun off a shell of gas and dust, making it look red. The shell soon dissipated, though, allowing the star’s true color to shine through.
 

Script by Damond Benningfield

Regulus, the bright star that marks the heart of the lion stands quite close to the lower left of the Moon at nightfall. The lion’s head and mane spread out to their right, with his long body to the upper left.

LAUNCH CONTROL: T-minus 30 seconds, and the countdown continuing to go smoothly. ...

Skylab — the first American space station — was going to be a fixer-upper. It was damaged during launch on May 14th, 1973. So when the first team of astronauts headed for the station 50 years ago today, it had a lot of work to do.

LAUNCH CONTROL: 5, 4, 3, engine sequence start, 2, 1, zero. We have launch commit, and we have liftoff! The clock is running, and Skylab has cleared the tower. CONRAD: Houston, Skylab 2. We fix anything!

But the “fixing” wasn’t easy. Astronauts Pete Conrad, Joseph Kerwin, and Paul Weitz set out to repair their damaged home. It had lost a protective shield and one of two solar panels, with the other one jammed shut. If the astronauts couldn’t fix the problems, they’d have to come home and let the next crew take a shot.

And at first, things didn’t go well. A tool designed to free the jammed solar panel didn’t work. And at the end of the first day in orbit, their Apollo spacecraft wouldn’t link up with the station. They had to take the docking system apart to fix the problem.

The crew moved into Skylab, then deployed a cover to bring down the temperatures. And ground controllers eventually worked out a way to fix the balky solar panel. So the mission continued. The astronauts studied Earth, the Sun, and how their bodies reacted to a record 28 days in orbit — a record that stood until the next Skylab mission later that year.
 

Script by Damond Benningfield

Some of the bright lights of winter are dropping from the evening sky. Look for Procyon in Canis Minor, the little dog, low in the west as nightfall. And look to its upper right for the twins of Gemini above Venus, the Evening Star.

As darkness falls, the Moon stands almost due west, more than a third of the way up the sky. Mars is close below it, and looks like a fairly bright orange star. Venus, the Evening Star, is to their lower right. And the star cluster M44 is close to the Moon’s left.

The western sky is pretty crowded tonight. The Moon and the planets Venus and Mars join the usual lineup of stars, including the twins of Gemini and a busy star cluster known as the Beehive.

As darkness falls, the Moon stands pretty much due west, more than a third of the way up the sky. Mars is close below it, and looks like a fairly bright orange star. Venus is off to their lower right — the brilliant “evening star.”

All three of these bodies are in constant motion against the background of stars, which are much, much farther away. The Moon’s motion is obvious from one night to the next — it moves by more than the width of your fist held at arm’s length. Tonight, the star cluster M44 is close to its left. Through binoculars or a telescope, the cluster looks like a bunch of angry bees buzzing around their hive, so it’s also known as the Beehive. By tomorrow night, the Moon will have moved well away from the cluster.

Venus and Mars move more slowly, but it doesn’t take long to notice a difference — especially when they’re close to such prominent stars as Pollux and Castor, the twins of Gemini.

Pollux is directly above Venus tonight, with Castor to its right. By late next week, though, Venus will line up side by side with the bright stars. At the same time, Mars will be passing directly in front of the Beehive — a long way from its current location.

Tomorrow: Patching up the first American space station.
 

Script by Damond Benningfield

Pollux and Castor, the twins of Gemini, stand to the Moon’s right and upper right this evening, with Pollux closer to the Moon. And to spice things up, Venus, the brilliant Evening Star, is close below them.

The twins of Gemini are pretty popular among the worlds of the solar system right now. Mars lined up side by side with them last week, and Venus will join them next week. But tonight, it’s the Moon’s turn. Pollux and Castor stand to the Moon’s right and upper right this evening, with Pollux closer to the Moon. And to spice things up a bit, Venus is close below them — the brilliant “evening star.”

All of the close encounters are made possible by the location of the twins. They’re not far from the ecliptic — the Sun’s path across the sky. The Moon and planets travel close to the ecliptic as well. So when they slide through Gemini, they’re naturally going to pass near the twins — with Pollux always the closer one.

As the seasons change, though, so do the timing of those encounters. That’s because Earth basically has two “days” — one related to the Sun, and the other related to the rest of the stars.

It takes our planet 23 hours and 56 minutes to make one full turn relative to the panoply of stars. But during that time, Earth moves about one degree in its orbit around the Sun. So our planet has to rotate an extra four minutes to bring the Sun back to the same position in the sky — giving us a 24-hour day. On that clock, all the other stars rise and set four minutes earlier each day. So as the seasons change, the stars move across the sky — changing the timing of their encounters with the Moon and planets.
 

Script by Damond Benningfield

The Moon and four other bright objects look like they’re having a block party the next few evenings. The Moon looks up at its companions tonight, stands in the middle of them tomorrow night, and waves goodbye on Wednesday.

The brightest member of the quartet is Venus, the “evening star.” It far outshines everything else in the night sky other than the Moon, so you can’t miss it. It’s also by far the closest member of the quartet now, at a distance of about 75 million miles. The planet will move even closer well into August, when it will cross between Earth and the Sun. It’ll reach a minimum distance of just 27 million miles — closer than any other planet ever gets.

Mars, on the other hand, is moving away from us. It was at its closest and brightest in December, when it shined brilliantly. As it retreats, though, it’s fading. This month, it looks like a modest orange star, well to the upper left of Venus.

The final members of the quartet are Pollux and Castor, the brightest stars of Gemini. The twins maintain the same brightness all the time. They’re so far away that a few million miles in either direction just doesn’t matter. Pollux is about 34 light-years off, while Castor is about 50 percent farther.

Venus will line up with the twins in late May and early June, while Mars will leave them behind as it moves eastward against the background of stars.

More about the Moon and twins tomorrow.
 

Script by Damond Benningfield

The Moon, the Evening Star, and a few other bright lights look like they’re having a block party the next few evenings. The Moon looks up at its companions tonight, stands in the middle of them tomorrow night, and waves goodbye on Wednesday.

Mercury is just peeking into the dawn sky. It stays quite low, so you need a clear easter horizon to see it. It looks like a fairly bright star below brilliant Jupiter. It will brighten and move a little higher in the coming days, but will remain a tough target.

Mercury is just peeking into the dawn sky now. But it stays quite low, so you need a clear horizon to see it — and binoculars wouldn’t hurt.

Mercury is the Sun’s closest and smallest major planet. And if people ever colonize the solar system, it probably won’t be a popular posting.

For one thing, it has no atmosphere, so you’d need spacesuits to get around. Temperatures at the equator can soar to 800 degrees Fahrenheit. And a day on Mercury lasts 176 Earth days. On average, that means you’d have three months of daylight followed by three months of darkness.

You’d be a lot older on Mercury, too. Mercury orbits the Sun four times for every orbit that Earth makes, giving it four “years” for every one on Earth. So your birthday cake would need four times as many candles. Of course, you’d also get four times as many cakes.

The extra cake wouldn’t add much to your weight, though; if you weigh 150 pounds on Earth, you’d weigh just 57 pounds on Mercury.

The best places to hang out on Mercury would be its poles. The bottoms of some craters at the poles never see the Sun, so they may contain big deposits of ice — a way to keep the punch cold for those frequent birthday parties.

Again, look for Mercury quite low in the east before sunrise. It looks like a fairly bright star, below brilliant Jupiter. It will get a little higher and brighter in the coming days, but will remain a tough target.
 

Script by Damond Benningfield

Two of the brightest stars of spring are high in the sky this evening. Regulus, in Leo, the lion, is in the southwest, while yellow-orange Arcturus is in the southeast. Both stars will remain visible in the evening sky until well into summer.

Some stars are classified as “peculiar.” That’s because they show odd mixtures of chemical elements. They have higher amounts of radioactive elements and of rare earths — the kinds of things used in electric-car batteries.

One star stands out as the most peculiar of all: Przybylski’s Star, named for the astronomer who discovered its bizarre nature. It’s about 350 light-years away, in Centaurus, which pokes above the southern horizon at nightfall.

Some elements are common among the stars, while others are quite rare. And Przybylski’s Star shows a complicated brew of elements unlike any other star’s.

It has very low levels of iron, nickel, and other metals — as little as one-tenth the level seen in the Sun. But it has high levels of “rare earths” — elements that just don’t show up in other stars. It also appears to have high levels of some radioactive elements that decay in a few thousand years or less. Such elements should have long since vanished from Przybylski’s Star, which is about a billion and a half years old.

Scientists haven’t yet explained what’s going on. One possibility is found in the star’s rare combination of qualities: It’s hot, it has a strong magnetic field, and it spins very slowly. That could “levitate” atoms that normally would be mixed inside the star, bringing them to the surface where we can see them.

Whatever the explanation, Przybylski’s Star will remain perhaps the most peculiar of all stars.

Script by Damond Benningfield

A cosmic jellyfish floats through a giant cluster of galaxies. It has a twisting “tentacle” that’s 200,000 light-years long — a trail of gas that’s given birth to hundreds of thousands of stars.

Galaxy D100 is in the Coma Cluster, a collection of thousands of galaxies. It’s classified as a “jellyfish” galaxy. Astronomers have discovered dozens of them. All of them are wide, thin disks, with tentacles of gas dangling behind them. And all of them are members of big clusters.

A galaxy turns into a jellyfish as gravity pulls it toward the center of a cluster at millions of miles per hour. The falling galaxy plows through massive amounts of gas between the cluster’s galaxies. That forces gas out of its own disk. The gas forms long ribbons behind the galaxy — the tentacles of the jellyfish. Gas in the tentacles clumps together, giving birth to bright new stars and setting the tentacles aglow.

D100 began forming its tentacle about 300 million years ago. As gas was ripped from its disk, star formation shut down in the disk and began in the tentacle. Stars are being born in clumps that are a few hundred light-years wide. The largest clump is just outside the disk, and contains about 200,000 stars.

The Coma Cluster is in the constellation Coma Berenices, which is high in the sky at nightfall. D100 is plunging toward the center of the cluster, leaving a trail of young stars behind it.
 

Script by Damond Benningfield

The Coma Cluster, a collection of thousands of galaxies that move through the universe together, is in the constellation Coma Berenices, which is high in the sky at nightfall. Several of its individual galaxies are visible through binoculars.

The stars are vanishing. Don’t worry, they’re all still there. It’s just that most of us can’t see them. And a recent study says the problem is even worse than expected.

The problem is called skyglow. It’s a glare caused by streetlamps, billboards, and other outdoor light sources. A lot of their light shines up into the sky. It reflects off of molecules and particles in the atmosphere, filling the sky with light.

Scientists have used instruments aboard satellites to try to measure that light. In 2017, for example, a satellite found that light pollution around the world was increasing by about two percent per year.

But the satellite wasn’t sensitive to the wavelengths produced by LEDs, which today make up a huge fraction of the outdoor-lighting market. And the satellite couldn’t pick up the light that was being scattered from side to side.

So a scientist in Germany teamed up with Globe at Night — an online network of volunteers. They kept an eye on the night sky, and compared what they saw to charts showing different levels of skyglow. And what they reported was a lot worse than what the satellite saw. Around the world, skyglow is going up by almost 10 percent per year.

One researcher described it this way: If a child is born today in a city where you can see 250 stars at night, by the time it turns 18, it’ll see just 100 stars. The rest will be hidden by the glow of the not-so-dark night sky.
 

Script by Damond Benningfield

The stars are vanishing, erased by the increasing glow of streetlights, billboards, and other artificial light sources. A recent study found that skyglow is increasing by almost 10% per year, blocking more stars from view.

Although it looks a bit like a giant spider hanging upside down from its web, this is actually a stellar nursery--a vast cloud of gas and dust that's giving birth to new stars. Known as the Coronet cluster, it's in the constellation Corona Australis, the southern crown. The region was imaged in the infrared, which shines through the dust, revealing details that are hidden from view at the wavelengths visible to the eye. [European Southern Observatory/Meingast et al.]

Look for Mars well up in the west at nightfall. It looks like a fairly bright orange star. Tonight, it lines up with the twins of Gemini. The stars are to the right of Mars, with brighter Pollux closer to it.

In September of 2021, the Perseverance rover was working quietly on the surface of Mars when this happened: [AUDIO: dust devil]. It might not sound like much, but on Mars, it’s the most exciting thing you’re ever likely to see: a dust devil — a spinning column of air that’s like a mini-tornado. This one swept over the top of the rover, blowing away some of the dust that had settled on it.

Dust devils are common sights on Mars, just as they are in many regions of Earth. They form when the ground is warmed by the Sun, causing the air above it to rise. It forms a spinning vortex that crawls along the landscape. On Mars, dust devils can be more than a mile high and half a mile wide — much larger than on Earth. And as they blow the dust off the Martian rocks, they leave winding trails that look like abstract tattoos.

Dust devils may generate small crackles of electricity: lightning. They’re too small and faint to see. But giant dust storms may produce more powerful outbursts. Research says even those shouldn’t be strong enough to harm either people or their machines. But they might produce a soft glow around a storm — the glow of dust blowing in the Martian winds.

Look for Mars well up in the west at nightfall. It looks like a fairly bright orange star. Tonight, it lines up with the twins of Gemini. The stars are to the right of Mars, with brighter Pollux closer to it.
 

Script by Damond Benningfield

Anyone who’s self-conscious about their weight might not want to visit Jupiter. Surface gravity on the solar system’s largest planet is more than twice as strong as Earth’s. So a person who weighs 150 pounds on Earth would weigh about 380 pounds on Jupiter.

Jupiter doesn’t actually have a surface for you to stand on. The planet is a big ball of gas, with nothing “solid” until you drop tens of thousands of miles below its cloud tops.

For comparison purposes, though, scientists have come up with a definition for the “surface” of Jupiter and the solar system’s other giant planets. It’s the depth in the atmosphere where the pressure is equal to the surface pressure on Earth.

That’s far below the tops of Jupiter’s highest clouds. But there are zones in the atmosphere where the clouds aren’t nearly as high, so the “surface” isn’t necessarily below them.

All of this means that no one will ever walk on Jupiter. It might still be possible to visit the planet, though. Visitors could float through the sky in balloons or blimps, or cruise in specially designed aircraft. But the seats would need to be well padded — to handle the passengers’ extra weight on the solar system’s largest planet.

Jupiter is just climbing into view in the eastern dawn sky. It looks like a bright star, but it’s so low that you need a clear horizon to spot it. It’s easier to pick out tomorrow because it’s a whisker away from the crescent Moon.
 

Script by Damond Benningfield

Jupiter is just climbing into view in the eastern dawn sky. The giant planet looks like a bright star, but it’s so low that you need a clear horizon to spot it. It will be easier to pick out tomorrow because it will be a whisker away from the crescent Moon.

Skylab, the first American space station, headed for orbit 50 years ago, on May 14, 1973. It was designed to accommodate three astronauts at a time for up to 56 days per mission. The astronauts would study Earth, the Sun, and how their own bodies adapted to a long period of weightlessness. During launch, however, a protective shield broke away, tearing off one of Skylab's solar panels and jamming another shut. Without the missing shield, interior temperatures climbed to 130 degrees Fahrenheit. NASA had to delay the launch of the first astronaut crew while it devised a way to save the damaged space station. [NASA]

Spaceflight is never easy. Just ask the folks who operated Skylab, the first American space station.

It launched on May 14th, 1973. Just a minute into the flight, though, it was in trouble. A protective shield ripped away. It took a solar panel with it, and jammed a second one shut. Without the shield and the panels, there wasn’t enough power to support the station, and the temperature inside the lab soared to 130 degrees. The launch of the first crew of astronauts had to be scrubbed.

Skylab was as roomy as a three-bedroom house. It was designed to house three astronauts for up to two months at a time. They would watch Earth and the Sun, conduct experiments, and study how their bodies adapted to life in orbit. Unless engineers could find a way to fix the problems, though, the station would have to be abandoned.

It took a few days, but they worked out a plan. An astronaut would stand in the hatch of his Apollo spacecraft. He would use a pair of bolt cutters on a long pole to free the jammed solar panel. Later, another astronaut would poke a parasol through an airlock on the back of the station. It would open up and reflect the sunlight, bringing down the temperature.

And it worked. The first crew made the repairs, then started on its main mission. Two other crews followed. The last remained aboard for 84 days — a record that stood for several years — thanks to the efforts of the engineers who saved Skylab.
 

Script by Damond Benningfield

Ursa Major, the great bear, is high in the north on May evenings. The bear’s body and tail form the Big Dipper. The bear aims nose-first at the northern horizon.

This simulation depicts the merger of two neutron stars, which are the ultra-dense corpses of massive stars that exploded as supernovae. Recent work shows that as the neutron stars merge, they can revolve around each other at up to 78,000 times per second, generating gravitational waves that ripple through the universe. When the stars merge, that high-speed rotation would hold them up against their combined gravity, preventing the merged stars from collapsing to form a black hole -- for less than a second. Astronomers have found two possible such mergers in observations from the 1990s. [NASA/GSFC/STAG Research Centre/Peter Hammond]

A hypermassive neutron star defies gravity. Instead of instantly collapsing to form a black hole, it keeps itself puffed up. But only for a while. In the end, gravity always wins.

A neutron star is the ultra-dense corpse of a once mighty star. It’s more massive than the Sun, but smaller than the city limits of Chicago.

Neutron stars have a weight limit — about twice the mass of the Sun. If they pack on more, they collapse to form a black hole.

But there may be a way for a neutron star to hold up against that limit: from the merger of two neutron stars. If they come together in the right way, they might resist gravity by spinning extremely fast — up to 78 thousand times a minute.

That would churn up the surrounding space-time, producing tiny ripples known as gravitational waves. Future observatories should be able to “hear” those ripples as the stars approach each other, as depicted in this simulation. [audio]

The ripples would end with a “chirp” as the combined stars finally surrendered, forming a black hole. From merger to collapse, it should all be over in less than a second.

The black hole would “ring” like a bell for a while longer as it settled down, producing more waves. No one has yet “heard” that ringing. But a recent study found two candidate mergers from the 1990s. They were accompanied by intense bursts of gamma rays — bright flashes before the ultimate darkness.

More about gravitational waves tomorrow.
 

Script by Damond Benningfield

A star that’s moving into the final stages of life arcs high across the south tonight. Although the star is bigger and heavier than the Sun, its fate is the same: It will end its life as a hot cosmic cinder called a white dwarf.

The star is Rasalhague, the brightest star in Ophiuchus, the serpent bearer. It climbs into view in the east shortly after darkness falls, but climbs high across the sky during the night.

Rasalhague is actually a binary — two stars that are bound by their mutual gravitational pull. But only one of the stars is visible to the unaided eye. It’s more than twice as massive as the Sun, and about 25 times brighter. It’s much hotter than the Sun as well.

From this profile, astronomers deduce that the star is moving into the penultimate phase of its life: It’s becoming a giant. The star has fused the hydrogen fuel in its core to make helium, so the core is shrinking and getting hotter. Right now, it’s fusing the hydrogen in a thin layer around the core. As part of that process, the star’s outer layers are puffing up, making Rasalhague many times larger — a stellar giant.

When the giant phase ends, the star will cast its outer layers into space, leaving only its dense core — a white dwarf. Rasalhague will no longer produce energy, but it will still shine faintly because it’s extremely hot — the remains of a once giant star.

The Sun will go through the same series of changes — in several billion years.
 

Script by Damond Benningfield

Rasalhague, the brightest star in Ophiuchus, the serpent bearer, climbs into view in the east shortly after darkness falls, and climbs high across the sky during the night. Rasalhague is actually a binary — two stars that are bound by their mutual gravity.

The Moon looks like it’s rolling through a rack of bowling pins tonight — past the one-pin and heading for the next row, taking dead aim at the star Delta Scorpii. The whole group climbs into good view by about 11 or 11:30.

The one-pin is Antares, the brightest star of Scorpius. It’s close below the Moon. Despite our analogy, the Moon is actually moving toward the bright star, and will be even closer at dawn.

As seen from Earth, Delta Scorpii isn’t quite as bright as Antares. In reality, though, it’s just about as bright. In fact, it’s almost a twin to the Antares system.

Both Antares and Delta Scorpii are binaries — two stars linked by their gravitational pull. Each consists of a supergiant paired with a slightly less impressive star. The supergiants will explode as supernovas — probably within the next million years or so. The companion stars are right along the supernova mass limit, so they might explode, but they might not.

Pi Scorpii is to the right of the Moon. It’s a triple system. It consists of another Antares-like binary linked to a smaller star a long way away.

Antares and Delta and Pi Scorpii are all about the same age — roughly 11 million years to 15 million years. And they’re all members of the same huge complex of gas, dust, and stars. It’s given birth to many supergiants and near supergiants, plus thousands of smaller stars. And many more are taking shape — possible future “bowling pins” for the scorpion.
 

Script by Damond Benningfield

Antares, the brightest star of the scorpion, stands close below the Moon as they rise this evening. The star Delta Scorpii is to the Moon’s upper right. It doesn’t look as bright as Antares. In reality, though, it’s almost a twin to the Antares system.

The full Moon scoots low across the south tonight, shining on us from the constellation Libra, the balance scales. The constellation was created thousands of years ago, using parts of Scorpius, which rises to the lower left of Libra.

The full Moon scoots low across the south tonight, shining on us from Libra, the balance scales.

A couple of years ago, astronomers snapped the sharpest pictures of the Moon ever taken from Earth. They showed details as small as a few feet across — shot with radar. The images were a demo for a project to develop the most powerful planetary radar system ever.

Astronomers have been using radar for six decades. It told them how fast Venus turns on its axis and revealed ice at the poles of the planet Mercury. It’s also tracked some asteroids that could one day threaten Earth.

The most powerful radar used the giant Arecibo radio telescope in Puerto Rico. But it collapsed a couple of years ago. NASA’s Deep Space Network does some of the work, too. But its main job of tracking missions across the solar system keeps it busier and busier.

So astronomers built a transmitter that used less power than a microwave oven to beam radio waves from the Green Bank Telescope in West Virginia. A network of other antennas caught the reflections. The demo produced the images of the Moon and tracked an asteroid that was more than five times farther than the Moon.

Now, astronomers want to make the system a thousand times more powerful. That would let them map other planets and moons, discover hazardous asteroids at much greater distances, and track junk around Earth and the Moon — making the space around our planet a little bit safer.
 

Script by Damond Benningfield

The Moon will be full around midday tomorrow as it aligns opposite the Sun in our sky. May’s full Moon is known as the Milk Moon, Flower Moon, or Corn Moon.

TOI-5205b didn’t make astronomers work that hard to find it. But they did spend months learning the planet’s details, and they’re planning to learn even more.

Most of the more than 5,000 confirmed planets in other star systems were found when they passed across the face of their parent star, blocking some of its light. Often, that dip is so small that it can take a while to confirm that it’s real.

That wasn’t the case with TOI-5205b, which was discovered by a space telescope. The planet blocks seven percent of the star’s light — a huge fraction.

Astronomers followed up with several ground-based telescopes, including the Hobby-Eberly Telescope at McDonald Observatory.

The observations revealed that the planet is a little bigger and heavier than Jupiter, the giant of our own solar system. It’s huge compared to the star, which is about 40 percent the size and mass of the Sun, and it’s quite close in. The combination makes it unique among the exoplanets discovered so far.

Starlight filters through the planet’s atmosphere. Studying that light should reveal how and where the planet was born, how it’s moved, and more — details about a planet that doesn’t try to hide.

The TOI-5205 system is about 300 light-years away. It’s to the right of bright Cygnus, the swan, in the wee hours of the morning. But you need a telescope to see the star — even outside the dark passages of its giant planet.
 

Script by Damond Benningfield

Those GPS numbers on your smartphone pinpoint your latitude and longitude — your position on Earth’s surface. Latitude is your position north or south of the equator, usually expressed in degrees, minutes, and seconds. And longitude is your position east or west, in hours, minutes, and seconds.

Astronomers use a projection of those coordinates to define locations in the sky. Instead of latitude, though, the north-south position is known as declination. And the east-west position is called right ascension.

There’s a difference in the land-based and sky-based coordinates, though — the celestial ones change position. Earth wobbles on its axis, which causes the stars to shift around the sky. So when astronomers use a star’s coordinates, they have to specify time as well.

As an example, consider Spica, the brightest star in Virgo. Today, it’s at right ascension 13 hours, 26 minutes, 12 seconds, and a declination of minus 11 degrees, 17 minutes, and four seconds. But astronomers frequently use the location from the year 2000 to provide a fixed time. In that system, Spica is 13 hours, 25 minutes, 12 seconds, by 11 degrees, nine minutes, and 42 seconds — a slight but well-understood difference.

Tonight, there’s an easy way for most of us to spot Spica: It’s quite close to the Moon at nightfall, and stays close throughout the night.
 

Script by Damond Benningfield

Spica, the brightest star in Virgo, is below the Moon at nightfall, and gets even closer during the night. Spica is one of the more massive stars in our region of the galaxy. It’s likely to end its life with a titanic explosion known as a supernova.

Centaurus crouches low in the south around midnight for skywatchers in the southern states. The centaur is home to a mammoth stellar nursery, about 8,000 light-years from Earth. The nursery is giving birth to one of the more massive stellar infants yet seen.

A monster star appears to be taking shape in a cloud of gas and dust about 8,000 light-years from Earth. It may be more than 1300 times the mass of the Sun — one of the heavier “protostars” yet seen. What’s more, it’s feeding faster than any other protostar. So this amazing object could produce a monster star.

MIR 2 is in a stellar nursery in Centaurus. From the southern states, the constellation stands low in the south around midnight. The nursery is too faint to see without a telescope.

The nursery is young, so it contains few natal stars. But MIR 2 makes up for the lack of siblings. It accounts for about half of all the energy coming from the nursery.

Recent studies suggest the protostar is just 40,000 years old. So it offers a unique chance to study how such massive stars are born.

MIR 2’s birth is controlled by two forces. Gravity pulls in material from the surrounding cloud. Much of that infalling gas forms a ribbon that’s massive enough to form 500 stars the size of the Sun. At the same time, radiation and magnetic fields are pushing material away from the protostar. That may be blocking the birth of smaller stars.

MIR 2 won’t maintain its great heft. The heaviest stars yet seen are only a couple of hundred times the Sun’s mass. Even so, when the fires of nuclear fusion ignite, in a million years or so, MIR 2 should be a monster — one of the more impressive stars in the galaxy.
 

Script by Damond Benningfield

This ultraviolet image shows the Sun in 2019, during solar minimum, a period during which it produces few sunspots or solar flares. Activity is increasing, with a maximum forecast for 2025. The number of sunspots and other magnetic features has been above predictions for this cycle. [NOAA]

In the calendars of ancient Ireland and Scotland, May 1 was Beltane, a day dedicated to celebrating the end of winter and the start of summer. Beltane is a “cross-quarter” day, which comes roughly half-way between a solstice and an equinox.

The Sun isn’t behaving itself. Most forecasts for its current cycle said it should be quiet. But it hasn’t been. And the level of activity has been picking up.

The Sun goes through an 11-year magnetic cycle. At the cycle’s peak, the Sun is covered with more of the dark magnetic storms known as sunspots. It also produces more big outbursts of energy and particles.

Those outbursts can have a big impact on our technology. They can damage or destroy orbiting satellites, disrupt air traffic and radio transmissions, and knock out power grids on the surface. So scientists keep an eye on solar activity. And they produce both short-range and long-range forecasts to help operators know when to take precautions.

The last cycle was quiet. There were periods of days or weeks when there were no sunspots at all. That cycle ended in late 2019.

Forecasters expected the new cycle to be just as quiet. They expected it to peak in mid-2025, with an average maximum of about 115 daily sunspots — about a third less than the average peak.

From the beginning, though, the new cycle has been more active. There have been more sunspots, and more of the big outbursts known as solar flares. That includes several that are in the most powerful category — like category 5 hurricanes.

As with all forecasts, we can’t be sure what’ll happen next. But it sure looks like we can expect the Sun to be even more unruly over the next few years.
 

Script by Damond Benningfield

High technology highlights the southern evening sky at this time of year — the technology of the 18th century. A couple of small, faint constellations are named for the high-tech devices of the time.

Pyxis, the compass, is in the south-southwest at nightfall, just above the horizon. Antlia, the air pump, is to its left.

Nicolas Louis de la Caille created these and other technology-themed constellations in the 1750s. He journeyed to Africa to map parts of the sky that were difficult or impossible to see from Europe. From that, he drew some new constellations that covered fairly barren regions of the sky.

His constellations honored the telescope and microscope, the pendulum clock, and an early instrument for navigating at sea.

In the case of Pyxis, several of its stars once were part of the giant constellation Argo Navis — the boat that carried Jason and the Argonauts. La Caille split the constellation into thirds, with each part representing a section of the boat.

He then took a few stars that were part of the ship’s mast and turned them into Pyxis — a magnetic compass. Its brightest stars form a line that aims almost due north and south. Those stars are faint, though, so you need a clear, dark sky to see them

The stars of Antlia are even tougher to spot. They represent an air pump that had been invented by a French engineer a few decades earlier — a bit of 18th-century technology in the modern night sky.
  

Script by Damond Benningfield

The technology of the 18th century highlights the southern evening sky now. A couple of faint constellations are named for the high-tech devices of the time. Pyxis, the compass, is quite low in the south-southwest at nightfall. Antlia, the air pump, is to its left.

The Moon is in its gibbous phase now, so it is nice and bright. It stands high in the south at nightfall. And it has a bright companion tonight: Regulus, the star that marks the heart of the lion.

The Moon is a giant among the more than 200 known moons of the solar system’s major planets. It’s the fifth-largest and -most massive. It’s the second-densest. And it’s the largest compared to its host planet. As a result, some scientists consider Earth and the Moon to be a double planet.

To bolster that picture, the Moon is put together in a similar way to Earth. It has a dense core, made mostly of iron with a smattering of other metals. The core is wrapped in a layer of molten iron. In turn, that layer is wrapped in a partially molten layer of metals and rock. Then there’s a thick mantle of rocky materials, topped by a thin crust.

The crust isn’t the same around the entire Moon, though. On average, it’s about 40 to 45 miles thick on the near side, but about twice as thick on the far side.

That may be a result of the Moon’s relationship with Earth. The same hemisphere of the Moon always faces Earth — the reason we always see the same features. Asteroids and comets are pulled in by Earth’s gravity. As they approach the Moon, they’re more likely to hit the far side. The extra impacts build up a thicker crust — one big difference between the Moon and Earth.

The Moon is in its gibbous phase now, so it’s nice and bright. It stands high in the south at nightfall. And it has a bright companion: Regulus, the star that marks the heart of the lion.

Tomorrow: 18th-century technology in the southern sky.
 

Script by Damond Benningfield

The pure white ice of Antarctica is the best place on Earth to hunt for meteorites. Scientists have picked up about 50,000 of them there — almost two-thirds of all the meteorites ever found. And hundreds of thousands more may await discovery.

The process isn’t easy, though. An expedition takes months of planning and weeks of criss-crossing the ice on snowmobiles. But the hunters might have found a helper — the equivalent of a meteorite-sniffing hound dog: an artificial-intelligence technique known as machine learning.

Meteorites are bits of debris from asteroids and comets. Studying them helps scientists piece together the history of the solar system. And some of the meteorites come from the Moon and even Mars.

Meteorites are hard to find, though. Most of them look a lot like Earth rocks, so they blend in to the background. In Antarctica, they stand out.

Scientists fed information on where meteorites have been found in Antarctica into their computers. They also entered details on the ice, the weather, the contours of the rock below the ice, and other conditions. From that, the machines learned how to predict where meteorites are likely to be found.

The computers came up with 600 plots, each covering one and a half square miles. Comparing the map with known success rates in the plots that have already been scoured showed an accuracy of 80 percent. So the maps may yield better hunting for future expeditions.
 

Script by Damond Benningfield

Deimos, the smaller moon of Mars, passes in front of the Red Planet in this recently released image from Hope, a Mars orbiter operated by the United Arab Emirates. Hope's observations suggest that Deimos and Mars's other moon, Phobos, may be debris from an ancient impact between Mars and a large asteroid. The oddly shaped Deimos is less than 10 miles long. The image is a composite of 27 frames, which had varied exposure times to provide good views of both bodies. [Emirates Mars Mission]

The head and shoulders of Centaurus, the centaur, are visible from much of the U.S. They rise in late evening and remain in view, low in the south, for a few hours. The centaur’s body and legs are visible only from far-southern latitudes.

Modern astronomy is a data factory. Big surveys look at thousands or millions of objects. And even bigger surveys will observe even more objects in the decades ahead. Even with all the grad students in the world, though, there’s no way to look through all of those stars, galaxies, and other objects by hand.

Astronomers are using artificial intelligence for help. Clever algorithms and lots of computing power can sift through mountains of data to ID different types of objects. And they can point out the most interesting ones for detailed follow-up.

An example is a recent project by astronomers in India. They used machine learning to sift through 277,000 objects cataloged by an X-ray space telescope.

The astronomers fed all the details into their computers. They added some observations by other telescopes in space and on the ground. They then entered details about known X-ray objects. The computer software compared the known objects to those in the catalog. That taught it how to know what was what. With its new-found knowledge, it then categorized the objects in the catalog.

It identified 33,000 galaxies with giant black holes in their hearts; 16,000 X-ray stars; five thousand newly forming stars; plus dead stars, binary systems, and other objects. Astronomers can now use those objects in their studies of the X-ray universe — new raw materials from the astronomical data factory.

More about big data tomorrow.
 

Script by Damond Benningfield

The Moon will reach its “first-quarter” phase today at 4:20 p.m. CDT. Sunlight will illuminate precisely half of the lunar hemisphere that faces Earth. The Moon will grow “fatter” over the next week as the Sun lights up more of the Earth-facing side.

It takes a lot of help to study one of the biggest mysteries in the universe: dark energy. An experiment at McDonald Observatory, for example, has used three supercomputers and the eyes of 10,000 volunteers to sift through more than 60 terabytes of data. That’s resulted in the project’s first catalog — more than 200,000 objects.

HETDEX — the Hobby-Eberly Telescope Dark Energy Experiment — is looking at a million galaxies in a small patch of sky that includes the Big Dipper. The galaxies are giving birth to a lot of stars. They’re about 10 billion light-years away, so HETDEX sees them as they looked when the universe was young.

The goal is to see how fast the galaxies were moving away from us at the time. That will help scientists determine how the effect of dark energy has changed over time — and perhaps what dark energy is. Dark energy makes the universe expand faster as it ages. But scientists don’t know what it is.

The HETDEX catalog covers observations from the project’s start, in 2017, through the middle of 2020. It includes more than 50,000 of the type of galaxy the project is studying. But it also includes about 135,000 other galaxies and many other objects.

In addition, online volunteers around the world have classified a quarter of a million galaxies in the HETDEX observations — results for future catalogs.

We’ll talk about another big-data project tomorrow.
 

Script by Damond Benningfield

61 Virginis is one of the nearest star systems with known planets. Under dark skies, the star is bright enough to see with the unaided eye. It is a little to the lower right of Spica, Virgo’s brightest star, which is due south a couple of hours after sunset.

Stars twirl above the Hobby-Eberly Telescope at McDonald Observatory. A project known as HETDEX uses the telescope to probe the nature of dark energy. Project astronomers recently released their first catalog of observations, which includes galaxies, the remnants of exploded stars, binary star systems, and many other objects. We have more about HETDEX in the May/June issue of StarDate magazine. [Ethan Tweedie Photography]

Mars is named for the Roman god of war. That’s because the planet’s red color reminded Roman skywatchers of blood. But ancient Rome isn’t the only culture that named the planet for its vivid color. In ancient Egypt, it was “the Red One.” In China, it was “the fire star.” And in Arabia, it was simply “fire.”

Mars looks redder from afar than from up close. Pictures from orbiters and landers show that most of the surface has a more subtle hue: butterscotch. But big patches of it show other colors: gold, brown, tan, and even green. The color varies depending on the minerals at the surface.

And even in the red areas — make that butterscotch — the color is only skin deep. The color comes from a layer of powdery dust that coats much of the surface. Across most of the planet, it’s only a few millimeters thick. And even at its deepest, it’s only a few feet thick.

The dust consists of iron oxides — rust. On Earth, rust usually forms in the presence of water. On Mars, though, it may form from reactions with the atmosphere, or even from erosion by the winds. The winds blow the dust around, and suspend a lot of it in the atmosphere — making it look yellow or red as well. Beneath that veneer, the rock tends to be darker — chasing away the “red” in the Red Planet.

Look for Mars quite close to the Moon this evening. It looks like a fairly bright star. The glare of the Moon washes out its color — whatever it is.
 

Script by Damond Benningfield

Look for the planet Mars quite close to the Moon this evening. It looks like a fairly bright star. The glare of the Moon washes out most of its color, so it doesn’t really qualify to be called the Red Planet.

The first discovery of the Space Age was two intense radiation belts that encircle Earth. They’re called the Van Allen Belts in honor of James Van Allen, the scientist who led the team that found them. And scientists are still learning about them today.

The belts contain charged particles that are trapped by Earth’s magnetic field. Some of the particles come from the solar wind. Others are created by interactions between cosmic rays and Earth’s atmosphere.

The inner belt stretches from altitudes of a few hundred to a few thousand miles. The outer belt extends far beyond that. Most of the time, there’s a gap of a few thousand miles between them.

But a few years ago, a pair of probes — also named for Van Allen — found that the belts are dynamic. They expand, contract, and vibrate in response to storms on the Sun. At times, the gap between them can fill in, creating a single super-belt. The inner belt can expand to within just a couple of hundred miles of Earth’s surface. And the mixture of particles in the belts can change.

Understanding the belts is important for space flight. Most satellites generally stay below the belts. But any craft that spends much time in the belts gets zapped with a hefty dose of radiation — enough to fry unprotected systems. So spacecraft operators need to know what to expect from the belts so they can shield their hardware — from one of the many hazards of space flight.
 

Script by Damond Benningfield

This artist's concept shows a cutaway view of the Van Allen radiation belts, which are wide zones that trap charged particles from the Sun. The particles can damage spacecraft or people that transit the belts, so scientists study them carefully to more accurately assess the hazard. [NASA/GSFC/Scientific Visualization Studio]

Orion the hunter is putting in its final evening appearances of the season over the next few nights, low in the west at nightfall. Its most prominent feature is a short line of three stars called Orion’s Belt.

As we move toward summer here in the northern hemisphere, we can look forward to longer, warmer days. Most of the other planets go through cycles of seasons as well. But not Venus. There’s nothing to cause the seasons to change. So the climate stays the same all year across the entire planet.

Venus is the brilliant “evening star.” It’s below the crescent Moon this evening. The star El Nath is closer above the Moon, with Aldebaran, the bright orange eye of the bull, well to the lower left of Venus.

The seasons on Earth are caused by our planet’s tilt on its axis. For part of the year, the north pole tips toward the Sun, bringing longer, warmer days to the northern hemisphere. And for the rest of the year, the south pole tips sunward, bringing light and heat to the southern hemisphere.

Venus is flipped upside down compared to Earth and most other planets. But its tilt relative to the Sun is tiny — not nearly enough to create seasons.

The seasons on some planets are also influenced by their distance from the Sun. Mars’s distance varies quite a bit, for example, making the seasons in the southern hemisphere more extreme than those in the north. Here again, though, Venus is well behaved. Its distance from the Sun varies by less than any other planet — not enough to create any seasonal changes.

So daylight stays the same across the entire planet all year ’round, and so do temperatures — about 860 degrees Fahrenheit.
 

Script by Damond Benningfield

Venus, the brilliant Evening Star, perches below the crescent Moon this evening. The star El Nath is closer above the Moon, with Aldebaran, the bright orange eye of the bull, well to the lower left of Venus.

The Moon passes through some crowded territory the next couple of nights. Its most prominent companion is Venus, the beautiful “evening star.” Venus is close to the upper left of the Moon tonight. And a bright true star is a little farther to the left of the Moon: Aldebaran, the bright orange eye of Taurus, the bull.

And here’s something interesting about the trio — and about every other object in the night sky. We see all of them at the same moment in our own timeline — but not in theirs. We see the Moon, Venus, Aldebaran, and everything else as they looked at different moments in the past.

That’s because the universe has a speed limit — the speed of light. It’s 670 million miles per hour. But this speed limit is enforced by the laws of physics, so there’s no way to cheat and squeeze in a little extra.

As a result, it takes time for light to travel from a star or planet to our eyes. And the amount of time depends on its distance.

The Moon, for example, is a little less than a quarter of a million miles away, so the sunlight reflected from its surface takes about one and a third seconds to reach us.

Venus is almost a hundred million miles away right now — almost nine minutes at lightspeed. And Aldebaran is four million times farther than that. It takes light 65 years to cross that immense gulf — a distance of 65 light-years.

We’ll have more about the Moon and its companions tomorrow.
 

Script by Damond Benningfield

The Moon passes through some crowded territory the next couple of nights. Venus, the Evening Star, is close to the upper left of the Moon tonight. And a bright true star is a little farther to the left of the Moon: Aldebaran, the bright eye of Taurus, the bull.

The Lyrid meteor shower is at its best the next couple of nights. It is best viewed between midnight and dawn. The Moon sets early, so it won’t interfere. The shower was first recorded by Chinese astronomers in 687 BC—farther back than any other current shower.

A meteor shower that’s been around for at least 2700 years is at its best the next couple of nights. It’s best viewed between about midnight and dawn. And the Moon sets early, so it won’t interfere with the sparklers.

The Lyrid shower was first recorded by Chinese astronomers in 687 BC. That’s farther back than any other current shower.

Over the centuries, showers come and go. They’re produced by tiny grains of rock and dirt shed by comets or asteroids. That debris spreads out along the parent body’s orbital path. Earth flies through this path every April. The particles ram into our atmosphere at more than a hundred thousand miles per hour. They vaporize, forming the glowing streaks of light known as meteors or shooting stars.

But meteor showers don’t last forever. The orbits of Earth and the parent comets and asteroids naturally move out of sync. In addition, the comets and asteroids can be pushed around by the gravity of Jupiter and other planets. That changes their paths. So over time, meteor showers come and go. But the Lyrids have stuck around longer than any other shower yet recorded.

The Lyrids are named for Lyra, the harp. That’s because the meteors all appear to “rain” into the sky from near the constellation’s brightest star, Vega. They can zip across any part of the sky, though, so you don’t need to look at Lyra to see them. But the view is best after Lyra rises to prominence, around midnight.
 

Script by Damond Benningfield

M87 is a beast. The galaxy is bigger than our home galaxy, the Milky Way. It contains many more stars than the Milky Way — trillions in all — and has a total mass up to a couple of hundred times the Milky Way’s. And the black hole in its center may be a thousand times the mass of the Milky Way’s.

One thing that M87 doesn’t have is good looks. Instead of a beautiful spiral, it’s an elliptical galaxy. It looks like a fat yellow rugby ball, with a bright middle surrounded by a hazy puffball of stars. Astronomers aren’t sure how M87 got that shape, but they’re working on it.

Unlike spiral galaxies, where the stars all move in an orderly fashion, the stars in ellipticals move pretty much randomly. The stars’ orbits are stretched out. And ellipticals contain little gas for making more stars.

That may mean the galaxies formed from the mergers or two or more giant spirals. A merger could stir up the stars in the original galaxies, and trigger a huge outburst of star formation as clouds of gas ram together. The remaining gas would then be blown out of the galaxy.

On the other hand, ellipticals could have formed from the collapse of massive clouds of gas. That would give birth to many stars, which then blow away the remaining gas — creating plain but “beastly” galaxies.

M87 is well up in the east-southeast at nightfall, in the middle of a triangle formed by the bright stars Denebola, Arcturus, and Spica.
 

Script by Damond Benningfield

M87, one of the biggest and heaviest galaxies in our corner of the universe, is well up in the east-southeast at nightfall. It stands near the middle of a triangle formed by the bright stars Denebola, Arcturus, and Spica.

A solar eclipse will be visible from the Indian Ocean to Antarctica and into the western Pacific tonight as measured on American clocks. It will be total along some of that path, but annular along other parts, with the Sun encircling the Moon with a ring of fire.

A rare type of solar eclipse will play out tonight on American clocks, but few people will get to enjoy it. It’ll follow a narrow path from the Indian Ocean to the Pacific. The path will just nick the northwestern corner of Australia and the western tip of Indonesia. Most of it will cross open ocean.

The eclipse is a hybrid — a cross between an annular eclipse and a total eclipse.

All solar eclipses take place when the new Moon passes directly across the face of the Sun. In a total eclipse, the Moon completely covers the Sun, turning the sky dark. In an annular eclipse, the Moon is a little farther from Earth than average, so its disk isn’t quite big enough to completely block the Sun. Instead, a thin ring of sunlight surrounds the Moon.

The first and last hours of this eclipse will be annular. Between those periods, though, it’ll be total, with the Moon barely big enough to cloak the entire Sun. The eclipse gets under way at 9:37 p.m. Central Time, and ends more than four hours later. Viewers flanking the main pathway will see a partial eclipse, with the Moon covering a portion of the Sun.

Those of us in the United States won’t see a thing. But our time is coming. An annular eclipse will sweep across the western and southwestern U.S. on October 14th. Even better, a total eclipse will grace our skies next April 8th, along a path from Texas to Maine. So mark your calendars for these cosmic spectacles.
 

Script by Damond Benningfield

Globular star clusters are like skyscrapers in the suburbs. They’re densely populated structures surrounded by a lot of open space. Most of them are well outside the Milky Way’s disk. They’re tight balls of hundreds of thousands of stars, so they’re easy to spot.

An example is Messier 13, in the constellation Hercules. It climbs into view in the northeast by 9 or 10 p.m. Under dark skies, it looks like a faint smudge of light. Binoculars enhance the view.

M13 is about 25,000 light-years away. It contains several hundred thousand stars, packed into a ball about 150 light-years across. Most of its stars are right in the middle. They’re packed more than a hundred times tighter than the stars in our own galactic neighborhood. As a result, many more bright stars would speckle the skies of any planets in that region.

Most of those stars would look faint, and yellow or orange. That’s because M13’s original big, bright, blue stars have long since expired. The survivors are less massive than the Sun, and a good bit older. Such stars look redder and fainter than the Sun. A few stars have passed beyond the prime of life, so they’ve puffed up and gotten extremely bright. They’ll soon lose their outer layers, though, leaving only their hot but dead cores, known as white dwarfs.

A few stars in M13 have merged. That’s made them hotter, brighter, and bluer — the stand-out residents of a galactic skyscraper.
 

Script by Damond Benningfield

Messier 13, in Hercules, climbs into view in the northeast by 9 or 10 p.m. Under dark skies, the cluster looks like a smudge of light. Binoculars enhance the view. It contains several hundred thousand stars, all packed into a ball about 150 light-years across.

Most stars are born in bunches — great swarms that form from the collapse of a single cloud of gas and dust. The stars tend to stick together for a while in clusters. Over time, though, the gravity of the galaxy’s other stars and gas clouds pulls most clusters apart, so the stars go their own ways.

Even then, many of the stars can share a common motion through the galaxy — they move at the same speed, and in the same direction. Such associations are known as moving groups. And the title star of one such group climbs into view in the northeast in late evening at this time of year.

Zeta Herculis is at the top right corner of the Keystone, a pattern of four stars at the center of Hercules. It’s about 35 light-years from Earth. It actually consists of two stars. One of them is bigger, brighter, and heavier than the Sun. The other is less impressive than the Sun.

Decades ago, astronomers discovered that the system shares its motion through space with several other stars, which are spread across several constellations. That suggested that the stars were born together, so they were called the Zeta Herculis Moving Group.

Over the years, though, observations have been unable to confirm whether the stars are all the same age. So the stars of the moving group could be related — or they could just happen to share the same motion through the galaxy.

We’ll talk about a cluster in Hercules that has stuck together tomorrow.
 

Script by Damond Benningfield

The star Zeta Herculis forms the top right corner of the Keystone, a pattern of four stars at the center of Hercules. Zeta Herculis consists of two stars, which are about 35 light-years from Earth.

The Big Dipper stands high in the north late tonight, its bowl spilling its contents toward the northern horizon. Leo, the lion, stands in the southwest, while Cygnus, the swan, soars through the Milky Way in the northeast.

A body in the outer solar system has a ring, and it’s a bit vexing. It’s so far from its host world that it shouldn’t exist. Instead, theories of ring behavior say its material should have stuck together to form a moon.

The host is Quaoar — a dwarf planet. It’s about 700 miles across — a third the size of our own moon. And it’s more than 40 times farther from the Sun than Earth is — in the deep freeze of the Kuiper Belt.

Over several years, astronomers used telescopes on the ground and in space to watch as Quaoar passed in front of four different stars. The way a star’s light fades reveals details about Quaoar, such as whether it has an atmosphere.

Instruments recorded flickers in the starlight shortly before and after each star passed behind the dwarf planet. That indicated the presence of something that’s not completely solid — a ring. It ranges from a few miles to a couple of hundred miles across.

The ring is about 2500 miles from Quaoar. Inside about half that distance, Quaoar’s gravity would keep the ring material from sticking together. At the ring’s current distance, though, a moon should form pretty easily.

The ring might be kept stirred up by Quaoar’s one known moon. Or in the extreme cold, the icy particles that make up the ring might be so hard that they bounce off each other. Whatever the reason, Quaoar has an inconvenient ring — one that hasn’t behaved the way it was expected to.
 

Script by Damond Benningfield

This artist's concept depicts a recently discovered ring encircling the dwarf planet Quaoar, which is in the Kuiper Belt, far beyond the orbit of Pluto. Computer models say the ring shouldn't be there, so planetary scientists are trying to explain its existence. Quaoar's moon, Weywot, is depicted at the left, with the Sun, roughly four billion miles away, at right. [ESA]

Many of the big moons of Jupiter and Saturn appear to have oceans of liquid water below their icy surfaces. And a recent study says that the big moons of Uranus may be “juicy” as well.

The study was led by Julie Castillo-Rogez of NASA’s Jet Propulsion Laboratory. Her team looked at the moons Miranda, Ariel, Umbriel, Titania, and Oberon. Titania is the largest, although it’s less than half the size of our own moon.

The team simulated what’s going on inside the moons. The researchers considered each moon’s size, distance from Uranus, likely composition, and other factors. They also considered an alignment of the moons millions of years ago that could have heated their centers.

The simulations showed that all but Miranda — the smallest of the five — could have oceans. They could range from a few miles deep, to as much as 30 miles for Titania. They could be kept liquid by the internal heat of the moons, or by ammonia or other compounds that lower the freezing point.

A proposed mission to Uranus would scan the moons. Uranus’s magnetic field might cause the oceans to create their own magnetic signatures. The craft’s instruments should be able to detect those signatures — confirming a few more “juicy” moons in the outer solar system.

Uranus is low in the west in the evening twilight. It’s to the upper left of the planet Mercury, which looks like a bright star. Through binoculars, Uranus looks like a faint green star.
 

Script by Damond Benningfield

Arcturus is the fourth-brightest star in the night sky. Look for it in the east as night falls. If you need help finding it, first locate the Big Dipper. Follow the curve of the dipper’s handle away from the bowl to “arc to Arcturus.”

Saturn, the second-largest planet in the solar system, appears near the Moon at dawn tomorrow. The planet looks like a fairly bright star, and will stand to the left of the Moon.

Saturn has more than 80 known or suspected moons, including several that are pretty big. And a recent study says it might have had another big one in the distant past. Named Chrysalis, it might have broken apart a hundred million years ago, forming Saturn’s rings.

Planetary scientist Jack Wisdom at MIT was intrigued by Saturn’s tilt on its axis. It’s a lot more severe than it should be. That means something must have knocked the planet over. The gravity of the giant planet Neptune could have done the job, but only under special conditions — perhaps provided by Saturn’s largest moon, Titan.

Titan is moving away from Saturn at about four inches per year. Simulations by Wisdom and colleagues showed that, as Titan moved outward, it changed a “wobble” in Saturn’s rotation. That brought Saturn and Neptune into sync, tilting Saturn over.

Chrysalis was orbiting between Titan and another moon. As Titan moved outward, the gravity of Titan and Chrysalis increased Saturn’s tilt even more. It also pushed Chrysalis into a more and more lopsided orbit. That eventually brought it so close to Saturn that it was ripped apart by the planet’s gravity. The debris spread out to form the rings.

That scenario matches many estimates of the age of the rings — evidence that Saturn’s rings could be debris from a vanished moon.

Saturn appears near our own moon at dawn tomorrow. It’s to the left of the Moon, and looks like a fairly bright star.
 

Script by Damond Benningfield

The constellation Crater, the cup, dribbles across the south on spring nights. Eight stars outline the cup, but they are so faint that you need a fairly dark sky to see any of them. That is only because they are a great distance away, though.

Knots and filaments of gas and dust spread across 10 light-years of space in this recent James Webb Space Telescope of Cassiopeia, the remnant of a massive star that exploded as a supernova thousands of years ago. The orange and red semicircle shows the glow of dust that's warmed as material from the explosion rams into it. Small knots of material closer to the center of the image represent gas and dust blasted out from the original star. [NASA/ESA/CSA/Danny Milisavljevic (Purdue), Tea Temim (Princeton), Ilse De Looze (UGent)]

The space around Earth is getting crowded — thousands of satellites orbit our planet. The space around Jupiter is getting crowded, too — with natural satellites. A recent spate of discoveries has brought the number of known moons to 95 — more than any other planet in the solar system. And many more probably are just waiting to be discovered.

The new moons are small — no more than about five miles in diameter. And most of them are a long way from Jupiter — they take at least 11 months to make a single orbit.

The discoveries were made by a group led by Scott Sheppard of the Carnegie Institution for Science. Sheppard’s been involved in the discoveries of 70 of Jupiter’s moons. It takes careful observations to find the moons because they’re small, faint, and far away from Jupiter.

Three of the newly found moons orbit in the same direction as Jupiter’s rotation on its axis. They probably are chips of larger bodies that were blasted apart by big impacts.

The other new moons orbit in the opposite direction. They may have been asteroids that were captured by Jupiter when they wandered close to the solar system’s largest planet.

The new discoveries vaulted Jupiter past Saturn, which has 83 known moons, although its numbers are likely to swell, too. And a recent study said that Saturn might have had another big moon that was pulverized by Saturn’s gravity, forming the planet’s rings. More about that tomorrow.
 

Script by Damond Benningfield

The Moon will be at last quarter tonight. It aligns at a right angle to the line between Earth and the Sun, so sunlight illuminates one-half of the lunar hemisphere that faces our way.

When the JUICE mission begins its trek to Jupiter later this month, it’ll be launched by one of the most powerful rockets on the planet, Ariane 5. And the probe carries more than three tons of propellants. Even so, it’ll need a lot of help to reach Jupiter, and to achieve its scientific goals.

JUICE is scheduled to enter orbit around Jupiter in 2031. But it can’t get there on its own. So as it loops around the Sun, it’ll stage some close encounters — three with Earth, and one each with the Moon and Venus. JUICE will “steal” a tiny bit of energy during each pass. That will give it a gravitational “kick,” which will boost its speed and sculpt its path.

The mission’s main goal is to orbit Ganymede, the solar system’s biggest moon. It appears to have a deep ocean of liquid water far below its surface. The ocean could be a habitat for life. And even if it’s not, studying Ganymede will tell us more about how Jupiter’s big moons formed, how they’re put together, and how they’re changing.

But JUICE will need more help to enter that orbit. It will stage more than two dozen flybys of Ganymede and Jupiter’s other big icy moons, Callisto and Europa — important targets on their own. JUICE will use each moon’s gravity to refine its path — like getting a free rocket burn with each pass. That will ensure that it reaches Ganymede at just the right time, angle, and speed — when it can use its own power to settle into orbit.
 

Script by Damond Benningfield

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[AUDIO: Ganymede radio]

That’s the “voice” of Ganymede, the largest moon of the planet Jupiter — radio waves recorded by a spacecraft in 1996. The waves tell us that the moon produces its own magnetic field — the only moon in the solar system that does so. And that helps us learn about Ganymede’s interior — including the likelihood that it has a hidden ocean.

Ganymede is the main target for JUICE, a European spacecraft scheduled to launch this month. It’ll enter orbit around Jupiter in 2031. It’ll make a couple of dozen close passes by Ganymede and Jupiter’s other big icy moons, Europa and Callisto. Then it’ll settle into orbit around Ganymede — the largest moon in the entire solar system.

Ganymede’s ocean appears to be about 60 miles deep, and it’s buried almost a hundred miles below the surface. It contains more water than all of Earth’s oceans combined.

Motions of the layers inside Ganymede generate the magnetic field, which was also “heard” by the Juno spacecraft a couple of years ago. Sloshing saltwater in the ocean may alter the field, causing a “wobble” in the moon’s auroras.

The ocean could have all of the basic ingredients for life: water, along with energy and minerals from volcanic “geysers” on the ocean floor. So it’s possible that Ganymede could host life. JUICE won’t tell us whether that’s the case. But it should provide new details about a giant ocean that’s hidden from view.

More tomorrow.
 

Script by Damond Benningfield

The constellation Puppis rows low across the southern sky on early-spring evenings. It represents the stern of the Argo, the boat that carried Jason and the Argonauts through many harrowing adventures.

The Jupiter Icy Moons Explorer (JUICE) keeps its eyes on Jupiter and the giant planet's four largest moons in this artist's concept. Scheduled for launch April 13, JUICE will make a series of close passes by the moons Ganymede (foreground), Europa (partially covering Jupiter), and Callisto (right) before settling into orbit around Ganymede. (The fourth moon, Io, at left, is not a target for the mission.) The three moons may have oceans of liquid water below their icy crusts, and JUICE will try to confirm them. [ESO/VPHAS+ team, et al.]

The planet Jupiter is hiding. It lines up close to the Sun, so it’s hidden in the glare. It won’t return to view for a few weeks. But European scientists and engineers are preparing to launch a mission to the solar system’s largest planet this month.

The planet Jupiter is hiding. It lines up especially close to the Sun, so it’s hidden in the glare. It won’t return to view for a few weeks. But European scientists and engineers know exactly where it is. In fact, they’re getting ready to send a spacecraft toward it this month. It’ll arrive in 2031 to study Jupiter’s three largest moons.

JUICE — short for Jupiter Icy Moons Explorer — is the most ambitious mission to Jupiter so far. While it orbits Jupiter, it’ll make a total of 26 passes by the moons Ganymede, Callisto, and Europa. Then it’ll settle into orbit around Ganymede — the first spacecraft to orbit any moon other than our own.

Scientists are interested in the moons because they’re thought to have oceans of liquid water below their icy crusts. And each of the oceans is thought to hold several times more water than all of Earth’s oceans combined. That means the moons are possible habitats for life.

Europa is considered the best candidate. There could be fountains of hot, mineral-laden water jetting from its interior into the ocean. That would provide the main ingredients for life: water, the right chemistry, and energy.

Because of the shape of its orbit, JUICE will swing past Europa only twice. But its instruments will look for thin spots in the ice and jets of water squirting through the ice. They’ll also peek into the top layers of ice — another first for a “juicy” mission.

More tomorrow.
 

Script by Damond Benningfield

Antares is a big spotlight. Not only is the star a brilliant beacon on its own, but it also lights up the stuff around it. In particular, it’s illuminating the Rho Ophiuchi complex — clouds and ribbons of gas and dust that are giving birth to more stars.

The complex is about 460 light-years away. Few stellar nurseries are closer. It’s named for one of the bright stars it’s created.

The complex consists of several clouds, plus some streamers that are dozens of light-years long. They’re sculpted by winds and radiation from hot, bright stars.

Some of the clouds and streamers reflect light from Antares and other big, bright stars. Others are energized by the stars, so they produce their own light. And still others remain dark — they’re dense and cold.

Those regions are where most of the new stars are being born. Astronomers have cataloged thousands of stars and potential stars there. Some have not yet flared to life. Others are no more than a million years old. The most massive will live short, brilliant lives, then blast themselves to bits — the same fate that awaits Antares in the next million years or so.

Antares stages a spectacular encounter with the Moon tonight. They climb into good view by about 1 a.m. Antares snuggles within a degree or so of the Moon. The Rho Ophiuchi complex spans about a dozen times the size of the Moon. It’s so faint that it’s best seen in photographs — lit up in part by bright Antares.
 

Script by Damond Benningfield

The Moon and Antares, the bright star that marks the heart of the scorpion, stage a spectacular encounter tonight. They climb into good view by about 1 a.m. Antares snuggles within a degree or so of the Moon.

Hydra, the water snake, is the longest of the 88 modern-day constellations, yet it’s also faint. In fact, from most cities, only one of its stars, Alphard, is easy to spot. It is about half way up the southern sky as night falls.

Hydra, the water snake, is the longest of the 88 modern-day constellations. It’s so long that it takes hours for the entire thing to climb above the horizon. Yet Hydra is also one of the fainter constellations. In fact, from most cities, only one of its stars is easy to spot.

Alphard is about half way up the southern sky as night falls. There are no other bright stars anywhere close to it, so you shouldn’t have much trouble picking it out.

Alphard is about 175 light-years from Earth. At that great distance, the fact that we can see it so clearly tells us that the star is pretty remarkable. In fact, it’s a giant — it’s puffed up to about 50 times the diameter of the Sun.

The star is roughly 400 million years old — less than 10 percent the age of the Sun. Yet it’s also about three times as massive as the Sun. Heavier stars “burn” through their nuclear fuel faster than less-massive stars, so they age more quickly.

Alphard is already entering the final stages of life. As it uses up the fuel in its core, its outer layers are puffing up. They get cooler as they do so, giving Alphard a reddish orange color.

In a fairly short time — astronomically speaking — those outer layers will stream off into space. That will leave only the star’s hot but dead core — a tiny remnant known as a white dwarf. It’ll be far too faint to see with the eye alone — depriving the water snake of its one bright light.

Script by Damond Benningfield

Vela represents the sail of the Argo, the ship that carried Jason and the Argonauts. The constellation is quite low in the south as darkness falls. It is home to one of the largest individual objects in the night sky: the remains of an exploded star.

The constellation Vela represents the sail of the Argo, the ship that carried Jason and the Argonauts. It’s quite low in the south as darkness falls this evening. Only one of its stars is much to look at. But if our eyes were more sensitive, we’d see that Vela is home to one of the largest individual objects in the night sky — the remains of an exploded star.

The Vela Supernova Remnant was born as little as 11,000 years ago as seen from Earth when a giant star exploded. The blast sent the star’s outer layers racing into space at a few percent of the speed of light.

This cloud of material continues to expand. Today, it’s dozens of light-years across. At a distance of about 800 light-years, that makes it look about as big as your fist held at arm’s length.

As the debris rams into surrounding clouds of gas and dust, it heats them and causes them to glow. That creates a thin but beautiful nebula. It contains a diverse brew of chemical elements created in the heart of the star, or in the supernova blast.

Not all of the star was destroyed, though. Its core was crushed to form a neutron star. This bizarre object is more than twice as heavy as the Sun, but only as wide as a mid-sized American city. It spins 11 times per second.

With each turn, a beam of radio energy sweeps across Earth, so the star “pulses” on and off — a pulsating beacon for the ancient Argo.
 

Script by Damond Benningfield

Bright blue stars sparkle in front of the Vela Supernova Remnant--an expanding cloud of gas and dust from an exploded star in the southern constellation Vela, the sail. The star exploded roughly 11,000 years ago as seen from Earth. Today, the remnant is dozens of light-years across. Its debris swirls around as it encounters surrounding gas, dust, and magnetic fields. All that remains of the original star, which was many times the mass of the Sun, is a neutron star--a dense ball about twice the Sun's mass but no bigger than a city. This image, snapped with a telescope at the European Southern Observatory in Chile, contains more than 550 million pixels, and is the most detailed view of the Vela Supernova Remnant to date. [ESO/VPHAS+ team. Acknowledgement: Cambridge Astronomical Survey Unit]

The Big Dipper is high in the northeast at nightfall. It appears to “pour” its contents toward the northern horizon and into the Little Dipper. This fainter dipper is anchored by Polaris, the North Star, which is at the end of the dipper’s handle.

56 Ursae Majoris is dying. The star has completed the prime stage of life. Now, it’s going through some changes. It’s puffed up to giant proportions. Eventually, it will shed its outer layers, leaving only its hot, dense core — a white dwarf.

A companion star has already expired. And its death might have had a big impact on 56 Ursae Majoris — 56 UMa for short — in more ways than one.

A recent study says the companion might be a neutron star — a corpse that’s even smaller and denser than a white dwarf. It formed when the star exploded as a supernova, a hundred thousand years ago. The star’s outer layers were blasted into space at a few percent of the speed of light.

Today, the stars are separated by about 23 times the distance from Earth to the Sun. At the time of the blast, though, they probably were closer. So the supernova shockwave could have stripped away some of the surviving star’s outer layers. The explosion also created a rich brew of chemical elements. Some of those may have been embedded in the surviving star — perhaps explaining some odd chemistry seen today.

The supernova also could have blown away the material around the stars, creating an empty “bubble.”

A neutron star isn’t the only possible explanation for the companion to 56 UMa — but it might be the best one.

Under dark skies, 56 UMa is just visible to the unaided eye. It’s in the east at nightfall, to the right of the bowl of the Big Dipper.
 

Script by Damond Benningfield

Spica, the brightest star in Virgo, climbs up below the Moon by about 9 or 9:30 p.m. tonight. It will be closer to the upper right of the Moon tomorrow night. Spica actually consists of two stars, only one of which is visible.

In astronomy, just because you can’t see something doesn’t mean you can’t study it. That’s the case for a lot of stars. Many systems consist of two or more stars. But in a lot of those systems, one or more stars are hidden from even the biggest telescopes.

A prime example is Spica, the brightest star in Virgo. That bright point is the combined light of two stars. But only one of them is visible.

H.C. Vogel discovered Spica’s dual nature in 1890. He used a spectroscope to break the star’s light into its individual wavelengths. That produced a “barcode” that revealed the star’s temperature, motion, and composition.

Vogel found a second barcode, which was quite faint. It was produced by a companion star.

Detailed study since then has provided details on both stars. The main star is so massive that it will blast itself apart as a supernova. It’s more than 20,000 times brighter than the Sun. The companion is a little less massive, but it’s still more than two thousand times the Sun’s brightness.

The two stars are only about six million miles apart. The smaller, fainter star is so close to the main star that it’s overpowered by the flashier star’s light. So while astronomers have been studying the faint star for more than a century, they’ve never actually seen it.

We can see Spica tonight near the Moon. It climbs up below the Moon by about 9 or 9:30. It’ll be closer to the upper right of the Moon tomorrow night.
 

Script by Damond Benningfield

As night falls this evening, look in the southwest for Sirius, the brightest star in the night sky. The light you see from the star tonight actually began its journey 8.6 years ago. That means the star is 8.6 light-years away.

When the United States and the Soviet Union sent the first robotic landers to the Moon, in the 1960s, they were lucky just to hit the Moon. But today’s missions are aiming for pinpoint landings — a requirement for reaching important scientific targets.

An example is called SLIM — Smart Lander for Investigating the Moon. It’s a Japanese mission that’s scheduled for launch within the next few weeks. It’ll share a ride to space with an X-ray telescope.

It’s Japan’s first lunar lander. And it’s designed mainly to evaluate the technology for precise touchdowns. The small craft will aim for a zone about the size of a football field. If it works, it’ll set the stage for more ambitious missions in the future.

SLIM’s target zone is near the Marius Hills Hole — a round pit that’s hundreds of feet wide, and perhaps 250 to 300 feet deep. It may be an entrance to a lava tube — a tunnel carved long ago by flowing lava. Such tubes hold clues to the Moon’s volcanic history. And they could serve as homes for future astronauts.

SLIM will carry a tiny passenger: a rover called Sora-Q. It was designed by the company that created the Transformers and other popular toys. It’ll fly to the Moon curled up to about the size of a baseball. On the Moon, its wheels will unfold and carry it across the surface.

It’ll take weeks for SLIM to reach the Moon. So it’ll be a while before we know if it achieved its main goal: a pinpoint landing on the Moon.
 

Script by Damond Benningfield

Corvus, the crow, is low in the southeast at nightfall and glides across the south during the night. Its four main stars form a pattern that looks like a sail. The brightest of the four is Gienah, which is about 350 times brighter than the Sun.

XRISM, a Japanese X-ray telescope scheduled for launch as early as this month, stares into space in this artist's concept. The telescope will study black holes, neutron stars, the remnants of exploded stars, and other powerful objects and events. [NASA/GSFC/Conceptual Image Lab]

The environment around a black hole is a maelstrom of superhot gas. Most of the gas funnels into the black hole, but some escapes in “jets” that fire out at almost the speed of light. The gas gets so hot that it shines mostly in X-rays. So to fully understand what’s going on around a black hole, we need to observe its X-rays. But Earth’s atmosphere absorbs X-rays, so we have to send telescopes into space to see them.

Japan is ready to do just that. It’s scheduled to launch an X-ray telescope called XRISM within the next few weeks.

Even from space, it’s not easy to catch X-rays — they zip into and even through normal mirrors. So X-ray telescopes consist of a set of concentric tubes that are coated in gold. X-rays skip off the surfaces of the tubes, like stones skipping off a pond, and into special detectors.

XRISM’s instruments will study many powerful objects and events. They’ll look at ribbons of hot gas inside galaxy clusters, for example. The temperature and speed of the gas helps astronomers understand the cluster’s birth and evolution.

XRISM also will study the chemical evolution of the universe — how different elements formed and were scattered through space. That will help us understand how and when the first stars were born, how the stars created new elements, and how those elements were incorporated into later generations of stars.

XRISM will share its ride to space with a mission to the Moon; more about that tomorrow.
 

Script by Damond Benningfield

The planet Mercury will be in good view in the early evening for a while, low in the west as twilight fades. It looks like a bright star, far below much brighter Venus, the brilliant Evening Star.

For a lot of skywatching, it’s all about the angles. That’s the case now for the planet Mercury. It’s in good view in the early evening, low in the west as twilight fades. It looks like a bright star, far below much brighter Venus, the “evening star.”

Mercury is the closest planet to the Sun, while Earth is the third planet out. That means Mercury’s orbit is entirely inside our own, so Mercury never moves very far from the Sun as viewed from Earth. At its best, it can be visible for a short time after sunset or before sunrise.

This is one of those “at its best” times. Over the next couple of weeks, the angle between Mercury and the Sun will offer a good view.

Mercury will actually climb a little farther from the Sun over that period, providing a few extra minutes to watch it. On the other hand, it’ll get fainter — the result of the change in its phase — like phases of the Moon.

The planet is moving closer to us. On April 11th, when it appears farthest from the Sun, it’ll be about 20 million miles closer to Earth than it is tonight. On the other hand, sunlight will illuminate a much smaller fraction of the hemisphere facing our way. Tonight, about three-quarters of that side is in sunlight. But by the 11th, only about a third will be lit up.

When you put the numbers together, Mercury will be less than half as bright then it is tonight — but still a nice target in the evening twilight.
 

Script by Damond Benningfield

Look for Regulus near the Moon the next couple of nights. The bright heart of Leo, the lion, stands below the Moon tonight, and to the upper right of the Moon tomorrow night.

Regulus has always been one of the most respected stars in the sky. Some of its earliest names referred to it as a king. Others have called it “the heart,” because it represents the bright heart of the lion. And some have combined the names.

The name “Regulus” has been in use for about 500 years. It comes from the Latin word Rex, which means “the king.” Regulus means “the little king” or “the prince.”

The idea that it’s a king among stars goes back thousands of years earlier, to ancient Babylon. The name was passed down to the Greeks, then the Romans, then to the later cultures of Europe — who passed it on to us.

Regulus earned its “royal” reputation for several reasons. It’s one of the brighter stars in the night sky. It lies almost directly atop the Sun’s path across the sky, which means the Sun crosses near it every year. And it’s part of a constellation that represents a powerful animal — the lion, king of the beasts.

In fact, Regulus also has several names related to the lion. One is Cor Leonis — heart of the lion. In Arabic, it’s Kalb al Asad, which means the same thing. Both versions probably were handed down from Babylon. Indeed, the Babylonians combined the king and the lion in a single name: “the star that stands in the breast of the lion: the king.”

Whatever you call it, look for Regulus near the Moon the next couple of nights. It’s below the Moon tonight, and to the upper right of the Moon tomorrow night.
 

Script by Damond Benningfield

The ghostly glow of hot gas fills the space around the Spiderweb Galaxy in this recent image. The gas was imaged at radio wavelengths by an array of telescopes in Chile, while the background  galaxies were seen in visible light by Hubble Space Telescope. The Spiderweb is so far away that we see it as it looked almost 11 billion years ago, when the universe was only three billion years old. The Spiderweb is a member of a growing cluster of young galaxies, which are being pulled together by their mutual gravitational pull. [ESO/Di Mascolo et al./HST/H. Ford]

James Webb Space Telescope is just getting started. Yet astronomers are already planning for future generations of space telescopes. It’s a process that can take decades.

Webb itself took a quarter of a century. Initial concepts were proposed in the 1990s. It took a while to get approval, then it took a lot longer than promised to get it built and launched.

The concept for the next big space telescope, called Nancy Grace Roman, was devised more than a decade ago. If things stay on schedule, it’ll launch in 2027. It saved some time by using a telescope that was built as a spy satellite, but was donated to NASA.

The process takes so long for several reasons. For one thing, it can take many tries just to get picked. For another, space telescopes are complicated, and each one is unique, so it takes more years to build one. It also takes a lot of testing — no one wants to repeat the mistake that blurred the view of Hubble Space Telescope. And it takes more time to launch and get checked out.

Astronomers outlined plans for several new missions at a recent conference. The list included CASTOR, to provide Hubble-quality views of wide slices of sky; Event Horizon Explorer, a combination of space- and ground-based telescopes to photograph black holes; and HEX-P, to study everything from black holes to dark matter. None is guaranteed to make it to space. And even if one does, it’ll be years or decades from now — a long lead time for a new view of the universe.
 

Script by Damond Benningfield

The constellation Crater, the cup, is in the southeastern sky in early evening. Its stars are faint, so you need dark skies to find it. To ancient European cultures, Crater represented the birthplace of storms.

If you’re a city, town, coastline, bit of tundra, or even a desert and you don’t have your own spaceport, you’re behind the times. New rocket launch sites have been sprouting like Texas bluebonnets after a spring rain. And several more are scheduled to open later this year.

They’ll be launching some brand-new rockets, by new companies, built with new technology. That’s because the market for space missions is really taking off. The space industry will launch thousands of craft this year. Most of them are communications satellites. Others are tiny payloads that will conduct science and technology experiments. And a few will head for the Moon or carry astronauts to orbit.

Among the spaceports that have opened in the past year, or that are expected to open this year, are sites in Texas, Nova Scotia, Scotland, Cornwall, Shetland Island, and the Canary Islands.

They’ll launch some brand-new rockets. Many of them are made possible by new materials, 3D printing, and A.I. The list of first-time rockets includes Vulcan, Terran, and Prime. Some will carry thousands of pounds of payloads, while others will carry single satellites that weigh only a few hundred pounds.

The payloads also include craft that have carried people to space — or will in the next few years — from spaceports around the world.

Some of those sites will launch future space telescopes, and we’ll talk about planning for some of those tomorrow.
 

Script by Damond Benningfield

The insides of the planet Uranus are weird. Some models of the planet suggest it could have “diamondbergs” floating in an ocean of metallic liquid carbon.

Uranus is the seventh of the Sun’s major planets. And it may be the solar system’s weirdest planet, period. It’s the third-largest planet, but only the fourth most massive.

That’s one indication that most of Uranus consists of hot “ices” — water, methane, and ammonia. They’re heated by the great pressure in the mantle — the layer below the planet’s atmosphere.

There are several ideas about what’s happening in that layer. The most popular says that high temperatures in the mantle cause the methane to separate into its individual molecules. The carbon forms diamonds. They rain through the mantle, settling in an ocean around the core. The carbon is squeezed so tightly that it forms a metal. Electric currents in the ocean then generate the planet’s magnetic field.

It’s hard to know what’s happening, though, because only one spacecraft has visited Uranus — four decades ago. There are plans for a new mission, but it won’t get there for a long time — providing a better look deep into this weird planet.

Uranus stands close to Venus, the “evening star,” the next couple of nights. Uranus is easily visible through binoculars. It looks like a faint green star. It’s to the upper left of Venus this evening. It’ll be about the same distance to the lower left of Venus tomorrow night.
 

Script by Damond Benningfield

The planet Uranus stands close to Venus, the Evening Star, the next couple of nights. It’s easily visible through binoculars. It looks like a faint green star. It’s to the upper left of Venus tonight, and about the same distance to the lower left of Venus tomorrow night.

The planet Mars is well up in the west-southwest at nightfall. It looks like a bright orange star. Tonight, it’s below the first-quarter Moon, and leads the Moon down the western sky.

Phobos, the larger moon of Mars, could be one of the solar system’s most exciting thrill rides. But if you’re not careful, it could become a little too thrilling — one big push and you’d float off into space.

Phobos is a lumpy boulder that’s only about 15 miles in diameter. Its main feature is a giant impact crater. The impact almost blasted the moon to bits.

Phobos orbits just 3700 miles above the Martian surface. At that altitude, it moves so quickly across the Martian sky that it rises in the west and sets in the east, with moonrises about 11 hours apart.

Seen from Phobos, Mars would span about a quarter of the sky, and it would slide past at about 5,000 miles per hour. So in a single orbit around Mars — daylight permitting — you’d see everything from the giant volcanoes of Tharsis Ridge to Valles Marineris, a complex of canyons that dwarf the Grand Canyon here on Earth. But because of Phobos’s low altitude, you wouldn’t see the Red Planet’s polar ice caps — they’d be hidden around the curve of the planet itself.

You wouldn’t want to get too excited by the view, though. The gravity of Phobos is so weak that a single big jump would launch you into space — leaving the Martian moon behind.

Mars is in our own sky right now, well up in the west-southwest at nightfall. It looks like a bright orange star. Tonight, it’s well below the first-quarter Moon, and leads the Moon down the western sky.
 

Script by Damond Benningfield

The star El Nath is best known for its position in the sky. It forms the tip of one of the horns of the bull, so it’s nicknamed “the butting one.” And it stands directly opposite the center of the Milky Way Galaxy. But the star itself is interesting in its own right.

What we see as El Nath is a giant. It’s about five times the mass of the Sun, and more than four times the Sun’s diameter. And it shines about 700 times brighter than the Sun.

The word “giant” doesn’t apply only to the star’s size, though. It also describes its phase of life. El Nath is only about a hundred million years old — a few percent the age of the Sun. Because of its extra weight, though, it aged much, much faster. It’s already passed through the prime of life, and is into the next phase. As that phase continues, the star will get even bigger and brighter.

El Nath is also intriguing because there are hints that it has a companion. In one study, astronomers split the star’s light into its individual wavelengths. That produced patterns that are like the star’s “barcode.” But there were hints of a second barcode. If it’s real, then El Nath has a companion star that’s too close and faint to see directly. But so far, no one has been able to confirm a companion for the butting one.

El Nath stands close to the lower right of the Moon this evening. And bright orange Mars is a little farther to the upper left of the Moon. More about Mars tomorrow.
 

Script by Damond Benningfield

The star El Nath stands close to the lower right of the Moon this evening. It forms the tip of one of the horns of Taurus, the bull, so it’s nicknamed “the butting one.” The bright orange planet Mars is a little farther to the upper left of the Moon.

20 years ago tonight, a little before midnight, a cosmic missile streaked above the Midwest. It startled witnesses across five states. It then exploded with the force of perhaps 500 tons of TNT, raining shrapnel on Park Forest, Illinois, near Chicago. Debris hit houses, cars, and a fire station. A several-pound fragment punched a hole in the roof of one of the houses, bounced around the top floor, and settled not far from the head of a sleeping teenager.

The missile was a small asteroid — a space rock. It slammed into Earth’s atmosphere at about 45,000 miles per hour. Its outer layers vaporized, forming a brilliant meteor. The pressure of its trip through the atmosphere then caused it to explode, raining fragments across the landscape — the most heavily populated region ever to be pelted by a major “rain” of meteorites.

Several dozen pounds of those chips have been recovered. Studies of them have shown that the original space rock was a fragment of a much larger asteroid that broke up about 470 million years ago. The original body was in the asteroid belt, between the orbits of Mars and Jupiter. It was made of rock, not metal.

There’s a lot of disagreement about details of the fragment that hit Earth. Estimates of its original size range from about four to 10 feet, and a mass of a couple of tons to about 15 tons — a big missile that exploded 20 years ago tonight.
 

Script by Damond Benningfield

The Big Dipper is high overhead this evening, with the bowl turned upside down. Link the two stars at the outer edge of the bowl and follow that line toward the horizon. The first moderately bright star is Polaris, the North Star or Pole tar.

The Big Dipper moves high overhead this evening, with the bowl turned upside down. As you take in the view, link the two stars at the outer edge of the bowl. If you follow that line down toward the horizon, the first moderately bright star you come to is Polaris. Earth’s north pole aims directly at the star, so it’s also known as the North Star or the Pole Star — it marks true north in the sky.

Another north pole stands at about the same height at that hour. It’s in Coma Berenices, a faint constellation that’s well above Arcturus, a bright yellow-orange star that’s low in the east.

That spot marks the north galactic pole — the projection of the north pole of the Milky Way Galaxy.

The galaxy is shaped like a disk. It’s about a hundred thousand light-years across, and about ten thousand light-years thick. If you draw a line through the center of the galaxy, at a right angle to the disk, and project it above the disk, it aims toward Coma Berenices.

When we look in that direction, we’re looking through a thin section of the Milky Way, so there aren’t many really bright stars in that part of the sky. Instead, we’re looking into intergalactic space. And in fact, a telescope reveals many other galaxies in that direction. More than a thousand of them form a giant cluster, known as the Coma Cluster — a beautiful collection of galaxies that stands due north.

Tomorrow: A shower of space rocks pelts Illinois.
 

Script by Damond Benningfield

The Pleiades star cluster, which is also known as the Seven Sisters, poses to the upper right of the Moon at nightfall. Binoculars will help you see the cluster’s stars through the glare. The stars form the outline of a tiny dipper.

The glowing band of the Milky Way is always tough to find. It’s so faint that you need to get far away from city lights to see it. But this time of year is especially challenging, because the Milky Way doesn’t soar high across the evening sky as it does in summer and winter. Instead, it brackets the sky — it’s low in the west after nightfall, and in the east before dawn.

It’s all a matter of perspective. During summer, Earth faces the center of the Milky Way Galaxy around midnight, so the galaxy’s crowded inner regions climb high overhead. And during winter, we face opposite the galactic center, so the galaxy’s faint outer precincts top the sky.

About now, though, we’re looking at a right angle to the galaxy’s disk around midnight — away from our galactic home and toward intergalactic space. You can see the Milky Way, but not at its best.

In early evening, it arcs across the west. Its path is traced by Sirius, the brightest star in the night sky, which is in the south-southwest; bright orange Betelgeuse, well to the upper right; and W-shaped Cassiopeia, low in the northwest.

And as Earth turns during the night, a different region of the Milky Way rotates into view before dawn. It arcs high across the east, from Cassiopeia — now in the northeast — to the Northern Cross and over to teapot-shaped Sagittarius in the south — a section of the Milky Way that will highlight the evening skies of summer.
 

Script by Damond Benningfield

The Milky Way arches between Gemini and Orion this evening. To find Orion, look for the line of three bright stars that marks Orion’s Belt, in the southerdy in early evening. To find Gemini, look for a pair of even brighter stars high in the east.

The Moon creeps up on the brightest point of light in the night sky tonight: Venus, the “evening star.” Venus stands above the Moon as they come into view. The gap between them will shrink as they set, a couple of hours later.

The Moon creeps up on the brightest point of light in the night sky tonight: Venus, the “evening star.” Venus stands above the Moon as they come into view. The gap between them will shrink as they set, a couple of hours later.

The Moon was “new” on Tuesday, as it crossed between Earth and the Sun, starting a new month-long cycle of phases. At sunset tonight as seen from the United States, it’s about two and a half days into that cycle — it’s two and a half days “old.” It’ll grow 27 days older before the cycle ends at April’s new Moon.

This evening, the Sun will light up only about seven percent of the side of the Moon that faces our way. It’s daylight in that slim crescent, and nighttime everywhere else.

A lunar night lasts about two Earth weeks. But on the Earth-facing side, the nights are quite bright. They’re lit up by earthshine — sunlight reflecting off of Earth. It’s just like moonshine here on Earth, but much brighter. Earth is much bigger than the Moon, and about three times more reflective. So a full Earth is dozens of times brighter than a full Moon. That’s a view to look forward to for the astronauts who are expected to travel to the Moon later in this decade and beyond.

Right now, Earth is more than 90 percent illuminated, casting its bright blue glow across the lunar landscape. From here on Earth, that glow is easily visible on the Moon’s nightside — the ghostly light of Planet Earth.
 

Script by Damond Benningfield

If you’re an astronomer who studies faint, wispy objects like spiral galaxies, then this is your time to shine. The Moon was new yesterday, so it doesn’t fill the sky with its glow. With the pesky moonlight out of the way, those faint galaxies will shine at their best.

One example is M63, a spiral galaxy in the constellation Canes Venatici. It’s in the eastern sky in early evening, and soars high overhead later on. It’s also known as the Sunflower Galaxy for its beautiful shape and color. It’s bright, so it’s visible through just about any telescope. But the moonless night makes it easier to see some of the details.

In some ways, M63 resembles our own galaxy, the Milky Way. It’s about the same size and mass. And it appears to have a central black hole, although if it does it’s a lot bigger than the Milky Way’s.

Also like the Milky Way, the outer edge of the galaxy’s disk is bent, and probably for the same reason: the gravitational pull of companion galaxies. In the case of M63, the companions appear to pull out long, faint ribbons of stars that show up in long-exposure photographs.

And there’s one more similarity: Both galaxies are surrounded by haloes of dark matter. It far outweighs the bright matter, so it exerts a strong pull on the galaxy’s stars and gas clouds. But the dark matter produces no energy of its own, so there’s no way to see it — no matter how dark the skies are.
 

Script by Damond Benningfield

M63, a galaxy in the constellation Canes Venatici, is in the northeast in early evening and soars overhead later on. It’s known as the Sunflower Galaxy for its beautiful shape and color. It’s visible through most telescopes, but the moonless night makes it easier to see.

The planet Jupiter is disappearing from view. It’s quite low in the west as night falls, and looks like a bright star shining through the twilight. It’s far below much brighter Venus, the Evening Star. Jupiter sets about the time the sky gets fully dark.

The planet Jupiter is disappearing from the evening sky. And tomorrow, it’ll briefly disappear from the daytime sky — but only along a narrow path across the southern hemisphere.

Jupiter is quite low in the west as night falls, so you need a clear horizon to spot it. It looks like a bright star shining through the twilight. It’s far below much brighter Venus, the “evening star.” Jupiter sets about the time the sky gets fully dark.

Jupiter is vanishing from the evening sky because of our changing perspective. It’s about to pass “behind” the Sun, so it’ll be hidden in the Sun’s glare. It’ll return to view — in the morning sky — in a couple of months.

For tomorrow’s daytime disappearance, Jupiter will be hidden by the Moon — an act called an occultation. It happens because both Jupiter and the Moon stay close to the ecliptic — the Sun’s path across the sky. They both stray from it a little bit, so most months the Moon passes right by Jupiter. When the alignment is just right, though, it passes in front of the giant planet, hiding it from view.

This occultation takes place during the daylight, so it’s visible only through a telescope — and only along a path through north and central South America and the southern Pacific Ocean.

Tomorrow evening, though, the Moon and Jupiter will stage a nice encounter. They’ll stand side by side in early evening — the crescent Moon and the “disappearing” planet Jupiter.
 

Script by Damond Benningfield

Spring arrives in the northern hemisphere today. It’s the vernal equinox, which marks the moment the Sun crosses the equator from south to north. It also rises due east and sets due west. All of Earth will see roughly equal amounts of daylight and darkness.

If it’s been a nasty winter where you are, then you have our sympathy. On the bright side, though, it’s almost over — spring arrives in the northern hemisphere today.

That doesn’t mean the weather will change overnight. The shift of the seasons is a long, slow process, not something that happens with the flip of a switch. It’s governed by the steady progression of the Sun across the sky, which is the result of the changing angle between the Sun and Earth’s poles.

At the start of spring — the vernal equinox — the Sun crosses the equator from south to north. Neither pole dips toward the Sun, so the entire planet will see roughly equal amounts of daylight and darkness.

Over the next three months, though, as Earth continues in its orbit around the Sun, the north pole will gradually dip toward the Sun. That will bring longer, warmer days to the northern hemisphere, and shorter, cooler ones to the southern hemisphere. It’ll also bring non-stop sunshine to the north pole — a “day” that will stretch almost six months from sunrise to sunset.

One other item of note is that the Sun rises due east and sets due west on the equinox. That’s not the case at other times of the year. As the Sun moves northward across the sky, its rising and setting points move northward, too. So the equinox is a good time to get your bearings right here on Earth — all part of the constant cycle of the seasons.

Another cycle in the sky tomorrow.
 

Script by Damond Benningfield

Puppis, which represents the deck of the ship that carried Jason and the Argonauts, stands well to the left and lower left of Sirius, the brightest star in the night sky, at nightfall. The entire constellation is in view if you’re south of about Dallas.

Vulpecula, the fox, doesn’t have a lot of impressive stars. But it sure has a lot of impressive dead ones. That’s where astronomers discovered the first neutron star — which also happened to be the first pulsar. And a few years ago, it’s where they discovered the first fast radio burst in our home galaxy — an object that’s also a neutron star.

A neutron star is the corpse of a massive star that exploded as a supernova. The star’s core collapsed to just a few miles across, but it’s more massive than the Sun.

The first neutron star was discovered in Vulpecula in 1967. It was emitting regular “pulses” of radio waves as it spun on its axis. So it was called a pulsar. Some pulsars steal gas from normal companion stars, which makes them spin up to hundreds of times per second. The first of those was discovered in Vulpecula as well.

And in 2020, another neutron star there suddenly produced short bursts of radio waves that didn’t sync up with how fast it spins — the first sighting of such an event in the Milky Way.

A recent study says it was a result of an outburst of charged particles. The star generates an extremely powerful magnetic field. A disruption in the field likely generated the “volcano” of particles. That slowed the star’s rotation by a tiny bit, producing the radio bursts — and another interesting “dead” star in Vulpecula.

The fox is in the northeast at first light, to the right of Cygnus, the swan.
 

Script by Damond Benningfield

Vulpecula, the fox, is a faint constellation. Unless you live away from city lights, you might not see any of its stars. To give it a try, look in the northeast at dawn, to the right of bright Cygnus, the swan.

Vulpecula, the fox, is a faint constellation. Unless you live away from city lights, you might not see any of its stars.

But that may not always be the case. It’s giving birth to some monster stars. When the “cocoon” around them clears away, some of the stars should be easy targets. And even before then, some of them will explode and briefly shine through the haze. Of course, you’ll have to wait a bit — it’ll take millions of years to play out.

The “monster” stars are part of the Vulpecula OB1 association. It’s a vast complex of stars, plus gas and dust that are forming more stars.

The association is named for its abundance of “O” and “B” stars. They’re the biggest, heaviest, and brightest of all stars. They can be dozens of times the mass of the Sun, and hundreds of thousands of times brighter.

We can’t see any of them with our eyes alone, though. The complex is about 8,000 light-years away, and the stars are still enveloped by gas and dust. Over time, that material will either collapse to form more stars, or it’ll be blown away. That will expose the stars to view.

Many of the stars will explode as supernovas. They’ll leave behind tiny, dense corpses — neutron stars or black holes. In fact, some stars in Vulpecula already have, and we’ll talk about them tomorrow.

The fox is in the northeast at dawn, to the right of bright Cygnus, the swan. But you need dark skies to see any of the fox’s stars — at least for now.
 

Script by Damond Benningfield

Monster stars are being born in this massive cloud of gas and dust. Known as the Vulpecula OB1 association, it's about 8,000 light-years away, in the faint constellation Vulpecula, the fox. The association is named for its large population of class O and B stars, which are the largest, hottest, and brightest stars in the galaxy. Despite their brilliance, the stars are still enveloped by gas and dust, so we can't see them with our eyes alone. This view was obtained by a space telescope that is sensitive to infrared wavelengths, which reveal otherwise hidden details in the complex. Over time, the cloud of gas and dust will either collapse to form more stars or it’ll be blown away, exposing the stars to view. Many of the stars will explode as supernovas. They’ll leave behind tiny, dense corpses -- neutron stars or black holes. In fact, some stars in Vulpecula already have. [ESA/Herschel/PACS, SPIRE/Hi-GAL Project]

Cancer, the crab, is well up in the east at nightfall and passes high overhead later on. Although it is part of the zodiac, its stars are dim. The brightest, Beta Cancri, is so faint you may not be able to see it from a suburb, let alone a city.

Our home galaxy, the Milky Way, is a vast collection of hundreds of billions of stars. And the population is growing. On average, the galaxy adds a few new stars every year.

Across the universe, though, the rate of star formation has slowed down by a good bit since the first era of starbirth. And it will continue to slow in the coming eons as the raw materials for making stars are used up.

Stars are born from giant clouds of hydrogen and other elements. Nuclear reactions in the cores of the stars “fuse” the hydrogen atoms to make helium, which in turn is fused to make even heavier elements. This process uses up the hydrogen. In fact, it’s dropped from about 75 percent of the total mass of the universe just after the Big Bang, to about 73 percent today.

That still leaves a lot of hydrogen. But it’s much harder to gather it up to make new stars. Much of it is already locked up in stars, so there’s not as much available for the big gas clouds that give birth to stars. In fact, some galaxies have already used up almost all of their supplies.

There’s still enough in gas-rich galaxies like the Milky Way to keep making stars for many, many billions of years. Eventually, though, almost all of the hydrogen will be incorporated into stars. And the little free hydrogen that remains will be so widely spread that there won’t be enough to coalesce to make more stars — and the stellar nurseries will go quiet.

Script by Damond Benningfield

M82, one of the most vigorous galaxies around, is in Ursa Major, the big bear. It stands to the upper left of the Big Dipper as night falls, and is visible through a small telescope. It is giving birth to far more stars than our home galaxy, the Milky Way.

Big storms bring big rains at this time of year. It rains on the Sun, too, mainly during its own stormy season.

The Sun produces big magnetic storms on its surface. The number varies across an 11-year cycle. At its minimum, the Sun can be storm free for days or even weeks. But at its peak, the cycle can produce dozens of dark sunspots, plus many big outbursts of particles and radiation.

Those outbursts blast billions of tons of hot gas out into space. Some of that material escapes into the solar system, where it can affect Earth and the other planets. On Earth, it can knock down satellites, cause power blackouts, and block some forms of radio communications.

But some of it forms big loops that trace out a storm’s magnetic field. And much of that material can “rain” back down on the Sun.

A recent study looked at that hot rain. It was the first study to compare the length and intensity of the rainfall to the power of the storms. It found that the rain can last anywhere from an hour to more than three days. The longest rains were produced by the most powerful storms. And storms of low intensity produced little or no rain at all.

That suggests that studying the rainfall can tell us more about the energy produced by the storms themselves. It might also tell us more about the Sun’s long magnetic cycle, and even contribute to predictions of the intensity of coming cycles — helping forecast more rainfall on the surface of the Sun.
 

Script by Damond Benningfield

Messier 3, an old, giant star cluster, ascends the eastern sky tonight, to the upper left of the bright yellow-orange star Arcturus, which climbs into good view by about 10 p.m. The cluster is visible through binoculars as a small, round, faint smudge of light.

A star cluster with a lot of deceptively young-looking stars ascends the eastern sky tonight. It’s to the upper left of the bright yellow-orange star Arcturus, which climbs into good view by about 10 o’clock. The cluster is visible through binoculars as a small, round, faint smudge of light.

Messier 3 is a tight ball of half a million stars known as a globular cluster. It spans a couple of hundred light-years, although most of its stars are jammed together in the middle. They’re so tightly packed that each star probably has thousands of neighbors within just five light-years; by comparison, only one star system is that close to the Sun.

Among M3’s myriad stars are many that appear to be much younger than they really are.

M3 probably was born more than 11 billion years ago. All of its most vigorous stars, which were bright and blue, have long since died. So the cluster’s remaining stars should be fairly red. Yet M3 contains quite a few blue stars, known as blue stragglers.

The leading ideas say these stars drank from a sort of stellar fountain of youth, making them look young again.

They probably have companion stars. In one possible scenario, the stars merge to form a single star, which would be hot and blue. In another scenario, one star dumps its cool, red outer layers onto its companion, making the recipient bluer.

Both processes appear to be at work in M3 — reinvigorating some old stars.
 

Script by Damond Benningfield

Shells of gas and dust race outward from WR 124, a hot, massive star about 15,000 light-years away, in this James Webb Space Telescope image. Known as a Wolf-Rayet star, it is about 30 times as massive as the Sun. WR 124 is tens of thousands of degrees hotter than the Sun and hundreds of thousands times brighter. The star has already shed enough gas to make 10 stars as massive as the Sun, forming the surrounding nebula, which is about 10 light-years across. Fairly soon -- within the next million years or so -- the star is likely to explode as a supernova. Webb imaged the star and nebula at infrared wavelengths, which are invisible to the human eye, and astronomers assigned colors to different wavelengths to show the nebula's structure and composition. [NASA/ESA/CSA/STScI/Webb ERO Production Team]

Astronomers have discovered a new twist on an old galaxy. They’ve been studying M33, the Triangulum Galaxy, for more than 350 years. But a new study found that it’s not quite what it seems.

M33 is low in the west-northwest at nightfall, to the upper right of brilliant Venus, and is visible through binoculars. It’s more than two and a half million light-years away.

M33 has been considered a “flocculent” galaxy. That means it forms a disk with a lot of spiral arms and parts of arms. But when astronomers recently peered into the heart of M33 with Hubble Space Telescope, they found some surprises.

They plotted 22 million stars — old, young, and very young. And when they traced out those groups, they found three configurations.

The youngest stars, which tend to be brighter, formed the flocculent structure — spiral arms all over the place. The young stars mainly fell into two arms, connected by a bar of stars across the middle. And the older stars formed a flatter disk than the youngsters, with almost all of them in the two arms and the bar.

It’s impossible to tell what the galaxy looked like when it was born. It could have been hit or side-swiped by another galaxy fairly recently. That might have left the older stars in their original bar-and-two-arms arrangement. At the same time, it could have triggered the birth of new stars and created the many spiral arms we see today — a new twist to an old galaxy.
 

Script by Damond Benningfield

M33, the Triangulum Galaxy, is low in the west-northwest at nightfall, to the upper right of Venus, the Evening Star. It’s visible through binoculars. Under clear, dark skies, some viewers can spot it with their eyes alone. It’s more than 2.5 million light-years away.

Leo, the lion, springs high overhead late tonight. Its two brightest stars mark opposite ends of the constellation. Regulus, the heart of the lion, is at Leo’s western edge. The second-brightest star, Denebola, marks Leo’s tail.

Green Peas are like living fossils. Not the hard little nuggets that get overzapped in the microwave. These are small, busy galaxy nuggets. Astronomers have found several of them in the modern universe. But in its very first picture, James Webb Space Telescope found some in deep space — when the universe was less than a billion years old. That makes the close ones living fossils — as one astronomer described them, the coelacanths of galaxies.

Green Peas were discovered in 2007. They were fairly close — within a couple of billion light-years. They’re dense, round knots a few thousand light-years across — a few percent the size of the Milky Way. They’re giving birth to many stars. They get their color from the glow of hot gas — a lot of it. The combination of gas and rapid starbirth means they’re pristine — they’re just starting to take shape.

Webb discovered three Green Peas in its first picture of the deep universe, which covered a tiny fleck of sky. They’re the same size as the modern Green Peas. They have the same structure and composition. And they’re at the same stage in life — they’re just getting cranked up, so they’re giving birth to a lot of stars.

But these Green Peas are 13.1 billion years old. That means we’re seeing them as they looked when the universe was only 700 million years old.

So the modern Green Peas are like living fossils — modern versions of some of the first galaxies in the universe.
 

Script by Damond Benningfield

Stars are big — really big. The Sun, for example, is more than a hundred times the diameter of Earth. But a few stars leave the Sun in the dust. Antares, the bright orange heart of the scorpion, appears to be about 700 times bigger. If the Sun were the size of an NBA basketball, then Antares would be bigger than the entire arena.

That size may not be constant, though. The star’s brightness can vary by a fair amount. That suggests that Antares is unstable, so it pulses in and out. Some studies say its diameter could vary by as much as 20 percent. Not to bury you in numbers, but that would be the equivalent of roughly 140 Suns.

Other studies suggest it’s not the whole star that changes. The changes in brightness aren’t regular, so there’s no way to predict when Antares will get brighter or fainter. That could mean that bubbles of hot gas many times bigger than the Sun are churning to the surface. New bubbles are hot and bright, so they could account for the change.

No matter what’s going on, it’s certain that Antares is one of the more massive stars in the galaxy. That means it’ll get a lot brighter at the end of its life. It will explode as a supernova, perhaps outshining the entire galaxy before its tiny corpse fades into the cosmic night.

Look for Antares near the Moon in the early morning sky. It’ll stand to the left or lower left of the Moon at dawn tomorrow, and to the right of the Moon on Tuesday.
 

Script by Damond Benningfield

Look for Antares, the bright orange heart of the scorpion, near the Moon in the early morning sky. It will stand to the left or lower left of the Moon at dawn tomorrow, and to the right of the Moon on Tuesday.

It’s time for an annual ritual: spring forward. Tonight, we set our clocks ahead by an hour as we switch to Daylight Saving Time. It will remain in effect until we “fall back” in December.

It’s time for an annual ritual: spring forward. Tonight, we set our clocks ahead by an hour as we switch to Daylight Saving Time.

The idea was first proposed in the 19th century. Germany and Austria-Hungary became the first countries to adopt it, in 1916.

The United States took it up late in World War I. The idea was that extending evening daylight would reduce energy usage, providing more resources for the war effort. And during World War Two, it was implemented year-round, with a two-hour difference from Standard Time.

After the war, states were free to do what they wanted. But in 1966, Congress passed rules for the whole country. States could opt out — Arizona and Hawaii still do — but they couldn’t implement DST year-round.

Today, the pluses and minuses of Daylight Saving Time are hotly debated. Some studies suggest there’s a slight decrease in energy usage, but others find no difference. Other studies find an increase in health problems, such as the risk of heart attack — but others don’t. And still other studies have reported evidence of more car accidents, while others find no change at all.

But the change always brings complaints — especially in the spring, when we lose an hour of sleep. Last year, the U.S. Senate passed a bill to make the change year-round, but it died in the House. So for now, most of us will keep springing forward in March, and falling back in November.
 

Script by Damond Benningfield

The Orion Nebula is in the south as night falls, below Orion’s three-star belt. Under mildly dark skies, it’s visible to the unaided eye as a hazy smudge of light. It’s easier to see if you look at it out of the corner of your eye.

The Orion Nebula is one of the most remarkable regions in our part of the galaxy. It’s a giant complex of clouds of gas and dust that are forming new stars. So far, it’s given birth to thousands of them, of all sizes. And many more are taking shape even now. But some of those stars are starting to shut down the process.

Astronomers looked at the nebula with SOFIA, an airborne observatory that was retired in September. In particular, they looked at what was happening at the rim of a giant bubble. It surrounds the Trapezium, a small group of especially hot, bright, massive stars.

Radiation and strong “winds” from those stars created the bubble in the first place, blowing away the surrounding gas and dust. The SOFIA observations showed that today, the Trapezium is producing big outflows of hot gas — like interstellar rivers. The outflows are drilling thousands of tiny holes in the bubble — making the rim as porous as a sieve.

As gas flows out of those holes, it rams into material outside the bubble. That blows away some of the gas and dust that might otherwise make more stars — helping shut down starbirth in the Orion Nebula.

The nebula is well up in the south as night falls, below Orion’s three-star belt. Under mildly dark skies, it’s visible to the unaided eye as a hazy smudge of light. It’s easier to see if you look at it out of the corner of your eye — the combined fires of thousands of young stars.
 

Script by Damond Benningfield

The success of NASA’s Artemis I mission last year means the agency is getting closer to sending astronauts back to the Moon. A crew could land on the Moon within a few years, spending up to a week on the surface. And within a decade or two, astronauts could be spending weeks or months there.

But it won’t be easy. There’s no air, and temperatures range from a couple of hundred degrees above zero to a couple of hundred below, so habitats and spacesuits will need to be airtight and well insulated. And the lunar day lasts about a month, which could mess with a person’s normal day-night rhythm.

There are many other hazards as well. With no protective atmosphere, the Moon is constantly bombarded by small space rocks, which could puncture spacesuits or living quarters. And with no magnetic field, it’s bombarded by radiation from the Sun and beyond. In fact, big solar storms could be deadly.

There are ways to protect the astronauts. Habitats could be buried under dust and rock, screening out most hazards. And spacesuits could be made of materials that are stronger than earlier suits. Scientists and engineers are working to make all of that happen — as astronauts prepare to return to the Moon.

The Moon climbs into good view by 9 p.m. or so. It’s followed a bit later by Spica, the brightest star of Virgo. The Moon will inch closer to the star during the night, and they’ll be just a couple of degrees apart at dawn.
 

Script by Damond Benningfield

The Moon climbs into good view by 9 p.m. or so. It’s followed a bit later by Spica, the brightest star of Virgo. The Moon will inch closer to the star during the night, and they will be just a couple of degrees apart at dawn.

Mars isn’t quite dead yet. A volcanic region on the planet appears to have stayed active for the past 500 million years. And it’s still producing tremors in the Martian surface.

Tharsis is the largest volcanic region on Mars. It consists of several giant volcanoes, including some of the largest in the entire solar system. It also includes hundreds of smaller volcanoes, plus many related features.

The volcanoes began building about four billion years ago. And many of them have kept building until fairly recently. We don’t see any eruptions today. But there’s evidence that some of them may have erupted within the past hundred thousand years — the blink of an eye on the planetary time scale.

And a recent study found that the activity may not be over yet — below the surface. Images reveal big boulder slides on the flanks of some of the volcanoes and other features — perhaps triggered by volcanic activity. And the InSight lander, which listened for marsquakes, heard activity in the region as well — including one of the most powerful quakes during its entire mission.

A research team says that probably means there are still pockets of molten rock below some Tharsis volcanoes — so at least part of Mars isn’t dead yet.

Look for Mars high in the southwest as darkness falls. It looks like a bright orange star. A true star stands close above it: El Nath, “the butting one” — the tip of the horn of Taurus, the bull.
 

Script by Damond Benningfield

Mars is high in the southwest at nightfall. It looks like a bright orange star. A true star stands close above it: El Nath, the tip of the horn of Taurus, the bull. A recent study says that a volcanic region on Mars may still be active, stirring up “marsquakes.”

Seven bright stars that outline the constellation Orion are all supergiants, the biggest class of stars. That includes the three stars of Orion’s Belt, which are roughly parallel to the horizon at nightfall, and a four-star rectangle around the belt.

Comets are as fickle as the weather — and just as hard to predict. A prime example is Comet Kohoutek. It was discovered in a picture shot 50 years ago today. And early predictions said it could become the “Comet of the Century.” Instead, it was a public relations bust. It became barely visible to the unaided eye, but most people never saw it.

Comets are balls of ice mixed with dust and rock. When they pass close to the Sun, they release gas and dust, forming a long, glowing tail.

The comet was discovered by Czech astronomer Lubos Kohoutek. It was farther away than any other comet yet seen, and it would pass quite close to the Sun in December 1973.

Based on its distance and brightness, astronomers forecast that it could become quite bright. But they warned that comets are hard to predict.

Even so, they showed a lot of enthusiasm, which caught on with the public and media. Astronomers observed the comet with telescopes on the ground, plus a Sun-watching space telescope and a craft en route to Mercury. NASA even delayed the launch of the final Skylab crew so the astronauts could watch the comet with telescopes on the space station.

Scientists detected water vapor coming off the comet, confirming long-held theories. And their studies suggested the comet was making its first close pass to the Sun. So while Kohoutek was a P.R. bust, it provided valuable insight into these hard-to-predict objects.
 

Script by Damond Benningfield

The Moon will be full at 6:40 a.m. CST tomorrow as it aligns opposite the Sun in our sky. The full Moon of March is known as the Sap Moon, Worm Moon, or Lenten Moon.

James Webb Space Telescope started out with a bang. Some of its first pictures revealed that the universe was churning out galaxies quite soon after the Big Bang. That pushed the start of galaxy formation much earlier than most astronomers had expected.

The pictures revealed 87 galaxies that look like they formed just 200 million to 400 million years after the Big Bang, which took place 13.8 billion years ago. Astronomers are using other Webb observations to confirm those ages. If even a small fraction of them are correct, the ideas about early galaxy formation may need to be revised.

In a second study, scientists looked at Webb images of 850 galaxies that are at least nine billion light-years away. They compared the pictures to those of the same galaxies snapped by Hubble Space Telescope. Webb has a sharper view, and its instruments are more sensitive to the types of light at which astronomers observe distant galaxies.

Team members found that the Webb pictures showed much more detail in the most-distant galaxies. Many of them were shaped like disks, like our home galaxy, the Milky Way. Others were well-defined balls. That tells us that galaxies were pulling themselves together when the universe was quite young.

Webb’s first images covered only a tiny portion of the sky. So astronomers expect to find many more early galaxies as the telescope takes a deep look at the rest of the universe.
 

Script by Damond Benningfield

Regulus, the brightest star of Leo, is to the right or lower right of the Moon at nightfall, and below the Moon before dawn. The star has served as a key calendar marker for many cultures, including ancient Persia, where it was one of the four “guardians of heaven.”

In most calendar systems, two objects play leading roles: the Sun and Moon. Their motions across the sky define the day, the month, and the year.

Yet some calendars have relied on other lights in the sky: the stars. The first appearance of a star in morning twilight told people that it was time to plant or harvest crops, or to move to a warmer climate for the coming winter. Or a star reaching its highest point in the sky at midnight told them that it was time for important rituals.

One of those markers is Regulus, the brightest star of Leo, the lion. It’s to the right or lower right of the Moon at nightfall this evening, and below the Moon before dawn.

Regulus was one of the most important stars of the ancient world. In Persia, it was one of the four “guardians of heaven,” so it was a key marker in the calendar.

And today, Regulus plays a role in the calendar of the Mayan people of Central America — the descendants of the ancient Mayan civilization.

When Regulus stands highest in the sky at midnight — which happens this month — villagers begin preparing the fields for crops. And they start planting mountain corn when the waxing Moon passes by Regulus in March — an important reminder that’s as easy as watching the stars.

Watch Regulus as it pops into view near the Moon in early evening, and stays close throughout the night. It’ll stand just below the Moon before it sets, a little before dawn.
 

Script by Damond Benningfield

If you happen to be looking at the constellation Cancer in a couple of hundred million years, you might see some fireworks — the merger of two supermassive black holes. Right now, they’re about 750 light-years apart — closer together than any other supermassive black holes within a long way of Earth. They’re spiraling closer to each other, and are expected to merge to form an even bigger black hole.

The black holes are part of a system known as UGC 4211. It’s about 500 million light-years away. Each black hole is more than a hundred million times the mass of the Sun. They’re at the hearts of separate galaxies, which are also merging.

A recent study said the merger should happen in a series of big steps. In the first step, gravitational interactions with stars moving between them will push the black holes closer together. After that, they may keep their distance for a while.

Next, friction with clouds of gas in the galaxies may give the merger a kickstart. And over the final 10 million years or so, the dance of the black holes themselves will produce gravitational waves — ripples in space and time. Those waves carry away energy, which will bring the black holes together — setting off a huge but brief display of fireworks.

Cancer is high in the sky at nightfall. Tonight, it’s above the Moon. UGC 4211 is much too faint to see without a telescope — for now.

Tomorrow: a bright calendar marker.
 

Script by Damond Benningfield

Cancer, the crab, is high in the sky at nightfall tonight, above the Moon. The constellation is home to a pair of supermassive black holes on a collision course. In a couple of hundred million years, they should merge in a brief but brilliant outburst.

NASA recently released this sequence of images captured by Hubble Space Telescope when the DART spacecraft rammed into the small asteroid Dimorphos, on September 26, 2022. In the top image, snapped just two hours after impact, "spikes" containing roughly 1,000 tons of dust radiate from the asteroid. In the second image, 17 hours after impact, the spikes have been sculpted by the gravity of the asteroid's larger companion, Didymos. And in the final panel, radiation from the Sun pushes material into twin tails that stretch thousands of miles from Dimorphos. Follow-up observations have confirmed that DART deflected the asteroid's orbit, suggesting that asteroids on course to slam into Earth might be deflected as well. [NASA/ESA/STScI/J. Li (PSI)]

Queen Berenice spreads her tresses across the eastern sky tonight. They form a tight spray of faint stars known as Coma Berenices. The constellation climbs into view in the east-northeast an hour or two after nightfall.

Astronomers continue to track an asteroid that took a big wallop a few months ago. The observations will tell us more about the asteroid. More important, they could help keep Earth safe from future threats.

Dimorphos is about 500 feet across. On September 26th, the DART spacecraft slammed into it at 14,000 miles per hour. The goal was to change how long it takes Dimorphos to orbit a larger asteroid, Didymos.

That’s important because many asteroids pass close to Earth. Some of them could someday threaten to hit us. One possible way to protect Earth is to ram something into the asteroid, altering its path just enough for it to safely pass us by.

DART was designed to test that technique. Scientists expected the impact to change Dimorphos’s orbit by about 10 minutes. As it turned out, the change was much bigger — about 32 minutes.

Part of the change was due to the impact itself. But the collision also blasted a huge amount of debris into space. That material acted as a jet, giving Dimorphos a big push. It also created a tail thousands of miles long.

Astronomers are studying that debris to learn about the asteroid. And late next year, Europe will send a craft to fly past Dimorphos. It’ll measure the size of the crater gouged by the impact. It’ll also look into the crater to determine the asteroid’s composition and structure — critical information in figuring out how effective DART’s impact really was.
 

Script by Damond Benningfield

Pollux and Castor, the twins of Gemini, appear near the Moon tonight. Pollux, the brighter twin, is closer to the Moon. Pollux is only 34 light-years away, which makes it is a fairly close neighbor. Castor is roughly 50 percent farther.

Traveling to any astronomical object beyond Earth takes time. Apollo astronauts left Earth at 25,000 miles per hour, yet it took three days for them to reach the Moon — our closest neighbor. And present-day missions take even longer.

Yet that’s nothing compared to the time it would take to reach the stars — even the closer ones. A couple of examples appear near the Moon tonight — Pollux and Castor, the “twins” of Gemini, with Pollux closest to the Moon.

Pollux is only 34 light-years away. A light-year is the distance light travels in a year — almost six trillion miles. So Pollux is about 800 million times farther than the Moon. An airliner traveling at about 550 miles per hour would need more than 40 million years to get there. And assuming it could maintain a constant speed, even an Apollo spacecraft would take a million years to cover the gap.

Castor is roughly 50 percent farther than Pollux. That means 60 million years by airliner and a million-and-a-half by spacecraft. There’s one caveat, though. Castor is a system of at least six stars, which makes it a little more difficult to measure its distance. So there’s an uncertainty of about three light-years. That means you could spend all that time in transit and find out that you still had hundreds of thousands of years to go — or that you flew past it and had to double back to reach this nearby star.
 

Script by Damond Benningfield

If you have a few minutes after sunset, it’s well worth stepping outside and peeking at the western sky. That’s the site of a spectacular encounter between Venus and Jupiter, the brightest objects in the night sky after the Moon. They stand side by side, separated by about the width of the Moon. Venus is the brighter of the two.

The planets are quite different. Venus is a ball of rock and metal only a little smaller and less massive than Earth. Jupiter is a ball of gas that’s much bigger and heavier than Earth. Yet both worlds have an effect on our own — a cycle in Earth’s orbit caused by a gravitational tug of war between Venus and Jupiter.

Jupiter is the most massive planet in the solar system, but Venus passes much closer to us. So when you work it all out, they both produce a pretty good tug on our planet. That changes the shape of Earth’s orbit.

Right now, the orbit is pretty close to circular, so our distance to the Sun varies by only about one and a half million miles in either direction. But over a period of about 400,000 years, the pull of Jupiter and Venus makes the orbit more lopsided. That causes the distance to the Sun to vary by about five million miles. That greater range produces a more significant difference in temperatures. And that creates big changes in climate — thanks to the pull of two planets that are staging a beautiful encounter in the evening sky.
 

Script by Damond Benningfield

The western evening sky is the site of a spectacular encounter between Venus and Jupiter, the brightest objects in the night sky after the Moon. They stand side by side, separated by about the width of the Moon. Venus is the brighter of the two.

The two brightest points of light in the night sky are staging a spectacular encounter. They’re low in the west at nightfall, and set an hour or so later. Venus is the brighter of the two — the “evening star.” Jupiter is a little above it tonight, but they’ll stand side by side tomorrow night — almost touching each other. They’ll stay fairly close for a few nights after that, but the gap will grow wider night by night.

Venus appears so bright because it’s close to Earth, it’s covered by bright clouds, and it’s close to the Sun, so it reflects a lot of sunlight into space.

Thanks to our always-changing viewing angle, the gap between Venus and the Sun will widen over the next few months. As a result, the planet will stand a little higher in the sky each evening until late June. It’ll be moving closer to Earth until August, when it will pass between us and the Sun.

Jupiter, on the other hand, is dropping toward the Sun. It will disappear in the evening twilight next month. Jupiter shines brightly in part because it’s the biggest planet in the solar system — roughly 11 times the diameter of Earth. And it, too, is covered by clouds. But its brightness is limited by its great distance — an average of almost half a billion miles.

Again, look for Venus and Jupiter hanging close together in the western sky not long after sunset — the brightest lights in the night sky.

More about Venus and Jupiter tomorrow.
 

Script by Damond Benningfield

The two brightest points of light in the night sky are staging a spectacular encounter in the west at nightfall. Venus is the brighter of the two — the Evening Star. Jupiter is a little above it tonight, but they will stand side by side tomorrow night.

The planets Venus and Jupiter, which are the two brightest objects in the night sky other than the Moon, will stage a spectacular close encounter in the western evening sky in late February and early March. They will slip past each other, with Venus climbing away from the Sun while Jupiter drops toward it. [Damond Benningfield/Stellarium]

With the end of winter still weeks away, people in colder climates may be dreaming of dips in a warm ocean under a steamy sky. And we know a couple of places where they wouldn’t have to wait for the change of seasons — a pair of “twin” planets orbiting a star in Lyra.

Kepler-138 is more than 200 light-years away. It consists of a star that’s much smaller, fainter, and cooler than the Sun, and perhaps four planets. Two of the planets are a little bigger and heavier than Earth. Such worlds typically are balls of rock and metal, just as Earth is. But these planets — Kepler-138 c and d — are different.

Studies with telescopes in space and on the ground showed that both planets are much less dense than Earth. But they’re too dense to be made of gas. Instead, they probably have dense centers surrounded by a layer of water more than a thousand miles deep.

The planets are so close to the star, though, that not all of the water is liquid. Each may have a thick atmosphere made of water vapor — like a giant steam bath. The atmosphere pushes down on the layer of water below, forming a deep ocean. But there’s probably not a sharp boundary between them. Instead, there may be a deep transition zone — part liquid and part gas — creating hot, wet worlds in a distant star system.

Lyra is high in the east at dawn, marked by its brightest star, Vega. But you need a telescope to see Kepler-138.
 

Script by Damond Benningfield

Kepler-138 consists of a small, faint star and perhaps four planets. Two of the planets may have dense centers topped by an ocean more than 1,000 miles deep. The system is in Lyra, which is high in the east at dawn, marked by its brightest star, Vega.

Families of stars almost always break up. Usually, members drift away gradually. Sometimes, though, some of them run away from the family group in a big hurry.

An example is Mu Columbae. It’s in the constellation Columba, the dove, which is low in the south as night falls. The star is about 1300 light-years away. But it’s so brilliant that, under dark skies, it’s visible to the eye alone — but just barely.

Mu Columbae is one of the more impressive stars in our part of the galaxy. It’s about 16 times the mass of the Sun, and perhaps 45,000 times brighter. And it’s moving at about 260,000 miles per hour relative to the Sun. That’s far zippier than all but a handful of other stars.

Astronomers have discovered that Mu Columbae is moving in exactly the opposite direction from another runaway star, in Auriga the charioteer. Tracing their paths backward shows that they converge at a pair of massive stars in Orion.

The leading idea says the runaways began their high-speed journeys about 2.6 million years ago. Two pairs of massive stars passed quite close to each other. They staged a fast, violent gravitational dance. The heaviest members of the two pairs changed partners, forming a new binary. The less-massive members of the original systems were kicked out. So instead of run-aways, the stars are actually kick-aways — stars kicked out of the family by their weightier siblings.
 

Script by Damond Benningfield

Mu Columbae is in Columba, the dove, which is low in the south at nightfall. The star is 1,300 light-years away, but under dark skies it’s just visible to the eye alone. It’s a “runaway” star, which means it’s moving much faster than the other stars around us.

Columba, the dove, sails low across the sky on February evenings. It’s due south as night falls now, but it’s so low that you need to be pretty far south to see it. Its brightest star, Alpha Columbae, is about 260 light-years away.

A faint dove sails low across the sky on February evenings. It’s due south as night falls now. But it’s so low that you need to be pretty far south to see it.

Columba is a recent constellation. Dutch mapmaker Petrus Plancius created it in the late 16th century. He carved it from a region with almost no bright stars. He called it Columba Noachis — Noah’s Dove. It represented the dove released from Noah’s Ark at the end of the biblical flood.

The dove’s brightest star is Alpha Columbae. It’s bright enough to see with the unaided eye, even though it’s about 260 light-years away. That means it really is bright — more than a thousand times brighter than the Sun.

The star is also much bigger and heavier than the Sun. And it’s spinning much faster than the Sun does. As a result, it’s flinging hot gas from its surface out into space. As that material cools, atoms link up to form solid particles, encircling the star in a cloud of dust.

Models of how stars evolve suggest Alpha Columbae is less than a hundred million years old — just a couple of percent the age of the Sun. Because of its great mass, though, it’s aging much faster than the Sun. That means it’s almost half way through the prime of life, when it steadily “fuses” hydrogen in its core to make helium. At the end of that phase, it’ll puff up to giant proportions and shine much brighter than it does now — making the dove much more prominent.

More about Columba tomorrow.
 

Script by Damond Benningfield

For New Horizons, the big moment of glory came in 2015, when it flew past Pluto. Yet its work isn’t done. The spacecraft is traveling through the Kuiper Belt — a zone of icy bodies beyond the orbit of Neptune, the Sun’s most remote major planet. It flew close to one of those bodies in 2019. Now, it’s scanning other members of the belt from long range. It’s also studying the outer regions of the Sun’s magnetic “bubble,” and looking into deep space.

New Horizons is expected to keep going into the next decade. So scientists are taking advantage of its position, more than five billion miles away. It’s near the edge of the Sun’s region of magnetic influence. It’s only the fifth spacecraft to journey that far. It’s headed in a different direction from the others, so it’s giving scientists a 3-D look at that zone.

The view of deep space from the Kuiper Belt is especially dark, so New Horizons’ instruments have a good view of it. They’ve discovered that the space between galaxies is brighter than expected. A recent study suggests that glow could be produced by particles of dark matter interacting with each other.

Astronomers are looking for new members of the Kuiper Belt for New Horizons to study. That’s resulted in the discovery of hundreds of objects. If things work out, they might even find one that New Horizons could fly close to — one last moment of glory for a hard-working spacecraft.
 

Script by Damond Benningfield

The star clusters M46 and M47 are in good view this evening, not far to the left or lower left of Sirius, the brightest star in the night sky, which is high in the south-southeast at nightfall. Under dark skies, M47 is just visible as a hazy patch of light.

The three brightest objects in the night sky line up as night falls. The planets Jupiter and Venus are below the Moon, in that order. Nothing else is anywhere close to their brightness, so you can’t miss them.

The Moon is the last of the three bodies to set, about 9:30 or 10. We won’t see it again until sunset tomorrow. If you just can’t wait that long, though, you can see bits of the Moon at more than 40 locations across the United States.

Those bits are from the Apollo missions. Astronauts collected almost 850 pounds of lunar samples. Hundreds of scientists around the world have studied the collection of rocks and dirt. Most of the remaining samples are stored in a lab at Johnson Space Center in Houston, where they’re still shipped out for study — and probably will be for decades to come.

But NASA has sent out many samples for public display. Most of them came from the final three Apollo missions. Most of the display samples are tiny — not more than a few grams.

They’re on display at NASA visitor centers, presidential libraries, and Smithsonian museums. Others are at state science and history museums, or at big aviation museums. According to NASA, they can be found in 23 states — from Massachusetts to California, Florida to Hawaii, plus Washington, D.C.

And if you’re outside the U.S., you’re not shut out: Lunar samples are on display in almost a dozen other countries.
 

Script by Damond Benningfield

The three brightest objects in the night sky line up as night falls. The planets Jupiter and Venus are below the Moon, in that order. Nothing else is anywhere close to their brightness, so you can’t miss them.

The Moon and the planet Jupiter stage a spectacular encounter this evening. Jupiter looks like a brilliant star next to the Moon. Venus, the “evening star,” is close below them, completing an impressive tableau.

Jupiter has four big moons of its own. And a spacecraft that’s been orbiting Jupiter since 2016 has recently turned its instruments toward three of them.

The biggest is Ganymede — the largest moon in the entire solar system. The Juno spacecraft flew just 650 miles from it in June of 2021 — the closest encounter with Ganymede in almost two decades.

Juno confirmed the moon has a deep ocean buried far below its icy surface. It also provided new details on Ganymede’s innards, and on the composition and temperature of some of its surface features.

Juno made a close pass by the moon Europa early last year. Europa has a buried ocean, too. But it’s much closer to the surface, and it’s considered a possible habitat for life. Scientists are still analyzing those observations.

And in December, Juno made the first of nine encounters with Io. It’s the smallest of the four big moons. Instead of ice and water, it’s a world of volcanoes — more than any other body in the solar system. Juno will pass less than a thousand miles from Io a couple of times.

The craft will continue its reconnaissance of Jupiter as well — telling us more about the solar system’s largest planet.

More about the Moon and its companions tomorrow.
 

Script by Damond Benningfield

The Moon and the planet Jupiter stage a spectacular encounter this evening. Jupiter looks like a brilliant star next to the Moon. Venus, the Evening Star, is close below them, completing an impressive tableau.

The planet Venus is the brilliant Evening Star. It’s in the southwest at nightfall. The planet Jupiter, the second-brightest point of light in the night sky, looms to its upper left. Tonight, the Moon is directly below Venus in the early twilight.

The last time the United States sent a mission to Venus, the first George Bush was president, and cell phones were as big as your head. Today, we’re getting ready to go back. NASA’s preparing two missions — one to orbit the planet, and the other to drop a probe into its atmosphere.

Venus is the second planet from the Sun. It’s a bit smaller than Earth. Its atmosphere is hot, dense, and toxic, and topped by clouds of sulfuric acid. Those clouds make it impossible to see the surface. But the last American mission, Magellan, which was launched in 1989, used radar to peer through the clouds. It mapped a surface covered by rugged volcanic features.

The new missions are Veritas and Davinci. Like Magellan, Veritas will use radar to map the surface. But its radar will be more powerful, so it’ll provide much better maps. Veritas also will map the composition of the rocks.

Davinci will orbit as well. But it’ll also drop a probe into the atmosphere. It’ll parachute through the clouds and go all the way to the surface. It should tell us more about how the atmosphere formed and evolved, and why it’s so different from Earth’s atmosphere.

Veritas is scheduled to launch no earlier than 2027, with Davinci following two years later.

Venus is the “evening star.” It’s in the southwest at nightfall. The planet Jupiter looms to its upper left. And tonight, the Moon is directly below Venus in the early twilight.

More tomorrow.

Script by Damond Benningfield

The star at the center of Orion’s Belt, a compact line of three bright stars that rolls high across the south on winter evenings, is Alnilam. It is the brightest of the belt stars even though it’s hundreds of light-years farther than the other two.

Iron is all around us. By mass, it’s the most common element in our entire planet. It makes up most of the core and a good bit of the crust. It even gives our blood its red color. And every bit of it was created inside stars.

All stars “fuse” together lightweight elements to make heavier ones. Right now, the Sun is fusing hydrogen, the lightest element of all, to make helium.

Stars like the Sun eventually make a few other elements, such as carbon and oxygen. But most of the elements beyond those are made inside much more massive stars, where temperatures are hundreds of millions of degrees higher. The fusion reactions produce energy, which makes the star shine and keeps it from collapsing under its own gravitational pull.

At the end of this chain of reactions is nickel-56, a radioactive element that decays to make iron. The iron can’t fuse to create heavier elements, so fusion stops. Without those reactions, the star’s core collapses. The layers around the core fall inward, then rebound in a titanic explosion — a supernova.

The explosion blasts many of the elements created inside the star into space. Over time, some of these elements — along with some even heavier ones created in the fury of the supernova — are incorporated into new stars and planets. So the iron that’s such a vital ingredient in our world and in our bodies was forged billions of years ago — in the hearts of stars.
 

Script by Damond Benningfield

There’s more than one way to gauge the brightness of a star. And the difference reveals important details about the star itself.

An example is Alpheratz — a binary star system that’s almost a hundred light-years away. Officially, it’s one of the brighter stars of the constellation Andromeda. But it’s also the brightest corner of the Great Square of Pegasus. Right now, it’s at the top of the square, which is low in the west and northwest at nightfall. It’s to the right of the brilliant planets Venus and Jupiter, so it’s easy to find.

One way to measure a star’s brightness is by its absolute magnitude. That tells us how bright a star would look to the eye from a distance of 10 parsecs — about 33 light-years. And on that scale, the brighter star of Alpheratz — star A — would look almost exactly 100 times brighter than the Sun.

But that’s only part of the story. On a scale known as luminosity, Alpheratz is 240 times the Sun’s brightness.

The difference is the result of surface temperature. Alpheratz A is many thousands of degrees hotter than the Sun. At that temperature, it shines a lot bluer than the Sun, which is yellow. More important, hot stars produce a lot more ultraviolet light than the Sun does. So when you add up all wavelengths, Alpheratz A shines even brighter — a brilliant corner of the Great Square of Pegasus.

Tomorrow: Even hotter stars whip up something heavy.
 

Script by Damond Benningfield

Alpheratz forms the brightest corner of the Great Square of Pegasus. Right now, the star is at the top of the square, which is low in the west and northwest at nightfall. It’s to the upper right of the brilliant planets Venus and Jupiter, so it’s easy to find.

Procyon, the Little Dog Star, is in the east-southeast at nightfall. It’s only 11.5 light-years away and it stands not far to the upper left of Sirius, the brightest star in the night sky. The combination makes Procyon easy to spot.

Extra weight can make a big difference in lifespan — whether it’s a person or a star.

Consider Procyon, the Little Dog Star. It’s actually a binary — two stars locked in orbit around each other. They were born together, a couple of billion years ago. But one of the stars was more massive than the other. As a result, it’s been “dead” for more than a billion years, while its companion has lived on.

Procyon is in the east-southeast at nightfall. It’s only 11 and a half light-years away, and it stands not far to the upper left of Sirius, the brightest star in the night sky. The combination makes Procyon easy to spot.

The system’s main star is Procyon A. It’s bigger, brighter, and heavier than the Sun. Procyon B is a dead stellar core — a white dwarf. It’s about 60 percent as massive as the Sun, but only about the size of Earth.

Procyon B was much heavier when it was born. Because of that, its core was much hotter than Procyon A, which revved up its nuclear reactions. That caused Procyon B to age much faster. After only about 700 million years, the reactions ended, the core collapsed, and the star’s outer layers were kicked off into space.

Procyon A was less massive, so it kept going. But today, it, too, is nearing the end. It’s making the transition to the next stage of life, which will end with the formation of a white dwarf as well. So Procyon will end as a pair of dead stars whirling through the darkness.
 

Script by Damond Benningfield

Mars stands high overhead at nightfall, and looks like a bright orange star. It’s not far from a fainter orange light, the star Aldebaran, which represents the eye of Taurus, the bull. They set by 2 or 3 a.m.

3.4 billion years ago, an asteroid the size of a town slammed into an ocean on Mars. It ripped up the sea floor, blasted rock and water vapor high into the sky, and changed the climate across the entire planet. It also generated a tsunami that raced a thousand miles in every direction, dropping boulders far from the impact site. And the first successful Mars lander, Viking 1, set down amid those boulders in 1976.

That’s the scenario outlined in a recent study. Researchers based their findings on the discovery of a large impact crater hundreds of miles from the landing site, and on computer simulations.

Before Viking touched down, scientists had expected to find smooth volcanic plains at the landing site, in a region known as Chryse Planitia. In fact, the site was chosen in part because engineers wanted a smooth, safe spot for the lander. Instead, Viking’s pictures showed lots of boulders.

The origin of those boulders has been a mystery. The new study provides a possible explanation.

The crater is about 60 miles across. It could have been gouged by an asteroid a few miles in diameter. The blast would have been at least 10,000 times more powerful than the largest H-bomb ever tested — creating a megatsunami on the surface of Mars.

Mars stands high overhead at nightfall, and looks like a bright orange star. It’s not far from a fainter orange light, the star Aldebaran. They set by 2 or 3 a.m.
 

Script by Damond Benningfield

Thousands of galaxies fill this view from James Webb Space Telescope. The bright white objects represent the glow of Pandora's Cluster, a collection of many giant clusters. Their combined gravity magnifies and distorts the view of more distant galaxies, which appear red. Many of the galaxies look stretched out as a result of the lensing effect of Pandora's Cluster. Some of these galaxies formed when the universe was quite young, giving astronomers a peek into what was happening many billions of years ago. [NASA/ESA/CSA/Ivo Labbe (Swinburne)/Rachel Bezanson (Univ. Pittsburgh)/Alyssa Pagan (STScI)]

The Moon glides past the Teapot—the figure formed by eight bright stars in the constellation Sagittarius—at dawn tomorrow. It will stand to the lower left of the handle.

Storms on the Sun can enhance or create storms here on Earth — from off-season typhoons in the western Pacific to ice storms in northern Canada.

The Sun produces giant magnetic storms. They generate outbursts of particles that can slam into Earth. The storms follow an 11-year cycle. At its peak, dozens of storms can blossom at the same time. At its low point, the Sun can go days or weeks with no storms at all.

Scientists first proposed a link between storms on the Sun and storms on Earth decades ago. Studies since then have supported the idea.

Two recent ones show links with off-season typhoons, and with winter storms in many parts of the globe.

The typhoons are in the western Pacific, near the Philippines and New Guinea. When the Sun is especially active, there’s an increase in the number of off-season typhoons. And they’re more likely to occur right after a solar storm reaches Earth. The Sun may trigger the typhoons by disrupting the circulation in the upper atmosphere.

The other study found a link between solar storms and massive winter non-tropical storms on Earth. In particular, it found that ice storms in Canada either broke out or grew stronger when jolts of solar wind hit Earth. Those blasts may create big waves in the upper atmosphere. The waves then heat lower levels of the atmosphere, triggering a series of events that intensifies storms at the surface — storms on Earth set off by storms on the Sun.
 

Script by Damond Benningfield

Shortly after sunset on any evening, look eastward to see Earth’s own shadow climbing into view. In a clear sky it forms a dark blue band below a band of bright pink or orange. The shadow climbs higher as the twilight fades.

In the rocket business, most of what goes up eventually comes back down. And either direction can be a problem for our planet’s atmosphere.

Studies have shown that rocket exhaust can increase temperatures in the upper atmosphere. That could influence hurricane formation, monsoons, and surface temperatures. It also creates chemical reactions that deplete the protective ozone layer.

And a recent study suggests that spacecraft reentering the atmosphere could cause problems, too.

Much of a spacecraft is made of aluminum. As it burns up in the atmosphere, the aluminum either vaporizes or disintegrates into small particles. The larger particles drop to the surface within hours. But the smaller ones can stay in the upper atmosphere for thousands of years. There, both the particles and the vapor can create chemical reactions that damage the ozone layer or form greenhouse gases, which contribute to global warming.

The number of launches is going way up. There were more than 180 launches last year, carrying about 2,000 satellites — both records. And the year before, more than 300 tons of satellites fell back to Earth. And all of those numbers are expected to keep going up in the years ahead. The new study says if those projections are right, then reentering satellites could add more than 550 tons of aluminum to the upper atmosphere every year. And that could be bad news for our changing environment.
 

Script by Damond Benningfield

Hydra, the water snake, slithers across the south tonight. It’s so big that it takes more than seven hours for the whole snake to rise. The stars that mark its head rise around sunset, while its tail clears the southeastern horizon after midnight.

Growing up in the Swiss Alps, Fritz Zwicky liked to throw rocks across rivers, and snowballs at church steeples. He just wanted to throw things higher and farther than anyone else.

Decades later, Zwicky became the first person to throw something away from Earth — a metal ball bearing blasted from the nose cone of a rocket. It escaped Earth’s gravity and went into orbit around the Sun. It was the first step in a grand plan to explore the solar system.

Zwicky was born 125 years ago today, in Bulgaria. After earning his doctorate in astronomy, he joined the Mount Wilson and Palomar observatories in California.

At the time, any star that suddenly flared into view was called a nova. But in the late 1920s, Zwicky realized that not all of these stars are alike. Some are far more powerful than others, so they’re called supernovas. Zwicky and a colleague also realized that a supernova should leave behind a crushed corpse, called a neutron star. The first one was discovered more than 30 years later.

Zwicky also served as research director at Aerojet Engineering. He studied jet engines, solar-powered furnaces, and colonies on the Moon. And he devised a five-step plan for human expansion into space — from “throwing” pellets farther into space, to reworking the planets and moons of the solar system to make them habitable.

The first four steps have all come about. But the last is still a bit more than a stone’s throw into the future.
 

Script by Damond Benningfield

The Coma Cluster consists of more than a thousand galaxies, all moving through space together. It is in the constellation Coma Berenices, which climbs into good view in the northeast by 10 or 11 p.m. Small telescopes reveal several of the cluster’s galaxies.

The Coma Cluster consists of more than a thousand galaxies, all moving through space together. Yet most of the cluster is invisible — it consists of dark matter. It produces no energy, but its gravity pulls on the visible matter around it.

The Coma Cluster provided the earliest evidence of dark matter. It was first suspected by Fritz Zwicky, who was born 125 years ago this week. We’ll have more about him tomorrow.

Zwicky was studying observations of the Coma Cluster made by Edwin Hubble, the namesake of Hubble Space Telescope. He found that many of the galaxies were moving too fast to be held by the gravity of the cluster’s visible matter. He surmised that some form of “dark matter” was contributing to the cluster’s total gravity.

But there were so many uncertainties in the observations that other astronomers didn’t buy it. It wasn’t until the 1970s that enough evidence began to pile up to convince most astronomers.

Today, we know that dark matter makes up about 85 percent of all the matter in the universe. Yet we still don’t know what it is. The leading idea has been that it’s a heavy subatomic particle. But searches have all come up empty. So new searches are focusing on much lighter particles — perhaps the “missing mass” of the universe.

The Coma Cluster is in the constellation Coma Berenices, which climbs into good view in the northeast by 10 or 11 p.m. Small telescopes reveal several of the cluster’s galaxies.
 

Script by Damond Benningfield

Black holes are everywhere — there could be a hundred million in the Milky Way Galaxy alone. And the closest one yet seen isn’t all that far away — just 1,560 light-years.

Astronomers discovered that one in observations from the Gaia spacecraft. It’s plotting the positions and motions of more than a billion stars. But it’s also making many new discoveries.

One of them is Gaia BH1 — its first black hole. Its images showed a star a lot like the Sun. The star was moving back and forth a bit — likely because of the gravitational pull of a companion. But Gaia didn’t see a companion. Neither did follow-up observations by other telescopes.

The companion had to be a black hole about 10 times the mass of the Sun. It’s probably the remnant of a star that started at about 20 times the Sun’s mass. The star’s core collapsed to form the black hole, while its outer layers blasted into space as a supernova.

The star and black hole are separated by about the same distance as Earth to the Sun. That’s the widest gap between the members of a black-hole binary system yet seen. And that’s a puzzle. Computer models say the two objects should be much closer. So astronomers are working to figure out what’s happening with this nearby black hole.

Gaia BH1 is in Ophiuchus the serpent bearer. The constellation is in the southeast at first light, to the upper left of the Moon. Gaia BH1 is far too faint to see without a telescope.
 

Script by Damond Benningfield

The closest black hole yet seen is just 1,560 light-years away, in Ophiuchus the serpent bearer. It’s in the southeast at first light, to the upper left of the Moon. Although the black hole has a companion star, the systm is too faint to see without a telescope.

The Crab Nebula stands high overhead in mid-evening. Small telescopes reveal a fuzzy blob of light with bright filaments that resemble the outline of a crab. The nebula is the debris from a once-mighty star that blasted itself to bits.

Most stars die in obscurity. The stars are so far away, and their final acts are so faint, that we never see them. But a year ago today, telescopes saw the death throes of a star that was 12 and a half billion light-years away. The star was ripped apart by a supermassive black hole.

The death was known as a tidal disruption event. Astronomers have seen several of them, but this was by far the most distant. The star was roughly the mass of the Sun. It swung close to a black hole at the heart of a galaxy. The black hole is about five million times the mass of the Sun — about the size of the black hole at the heart of the Milky Way.

The event was named AT2022cmc. It was first seen by an automated telescope that observes the sky at visible wavelengths. It soon was picked up by many more telescopes at many more wavelengths.

As the star approached the black hole, the black hole’s gravity ripped it apart in a blaze of light. About half of the star’s debris was captured by the black hole. It joined a disk of superhot gas around the black hole. The process produced shockwaves that generated X-rays and ultraviolet light.

Some of the material was flung away from the poles of the black hole in high-speed jets of particles and radiation. One of the jets was aimed at Earth, so the star’s death was especially bright — one of the brightest objects astronomers have ever seen.

We’ll talk about another black hole tomorrow.
 

Script by Damond Benningfield

A wide rings surrounds Quaoar, a dwarf planet in the outer solar system, in this artist's concept. The ring was discovered by CHEOPS, a European space telescope that is hunting for planets in other star systems. It discovered the ring by watching stars briefly disappear behind the ring as the telescope was aiming in Quaoar's direction. The ring presents a puzzle for astronomers because they expect such material to coalesce to form a moon. (Quaoar does have one known moon, Weywot, depicted at the left side of the illustration.) Quaoar is roughly 44 times farther from the Sun than Earth is, so the Sun (star at right) looks feeble. The dwarf planet is roughly 680 miles (1,100 km) in diameter. [ESA, CC BY-SA 3.0 IGO]

To the eye alone, Spica looks like a bright blue-white star. But the system is far more complicated. It consists of two massive stars locked in a tight orbit. The stars are so close that they distort each other. The bigger of the two pulses in and out like a beating heart. And even though the system is quite young, one of the stars is nearing the end of its life.

Spica’s main star is 11 or 12 times the mass of the Sun, more than seven times the Sun’s diameter, and more than 20 thousand times its brightness. The other star is a little smaller and fainter, but still impressive.

The official distance between the stars is about 12 million miles. But that’s measured from the centers of the stars. When you figure in the sizes of the stars, the distance is only about half of that — just a few percent of the distance from Earth to the Sun.

At that range, gravity distorts the stars. They puff toward each other, so they’re shaped like eggs. As they orbit each other, the angle at which we see them changes. That causes a small change in Spica’s overall brightness.

The system is only about 12 million years old — a tiny fraction of the Sun’s age. But the bigger star is near the end. In a few million years, it’ll explode as a supernova. After that, it’ll fade away, and Spica will lose much of its luster.

Spica is especially easy to spot tonight. It’s quite close to the Moon as they climb into good view, shortly before midnight.
 

Script by Damond Benningfield

Spica, the brightest star of Virgo, is especially easy to spot tonight. It’s quite close to the Moon as they climb into good view, shortly before midnight. Spica actually consists of two giant stars locked in a tight orbit.

Beta Monocerotis is one of the most beautiful triple star systems in the heavens — three blue-white points of light that make a skinny triangle. But the system is even more remarkable than it looks. All three of its stars are among the brightest and the most massive in the galaxy.

Two of the stars are roughly six times as massive as the Sun, and more than a thousand times brighter.

The third star probably orbits the other two. But it’s so far that it takes about nine days for its light to cross the vast gulf between them. So astronomers aren’t yet certain that it’s actually tied to them. Either way, it’s the most impressive of the triplets. It’s heavier than the others, and about twice as bright.

Like the Sun, all three stars will end their lives as cosmic embers known as white dwarfs. But they’ll get there a lot faster than the Sun. Heavier stars use up their nuclear fuel more quickly, so they live shorter lives. The stars of Beta Monocerotis will live less than one percent as long as the Sun before they enter the final phases of life. For a short while, before they become white dwarfs, each of them will shine much brighter than it is today.

For now, look for Beta Monocerotis in the southeast at nightfall. Although it’s the brightest star of Monoceros, the unicorn, it’s quite faint, so you need dark skies to see it. But it’s to the lower left of Orion’s Belt, so there’s a prominent marker to point the way.
 

Script by Damond Benningfield

Beta Monocerotis is one of the most beautiful star systems in the heavens: three blue-white points of light that make a skinny triangle. It’s in the southeast at nightfall. It’s the brightest star of Monoceros, the unicorn, but you need dark skies to see it.

To find Monoceros, the unicorn, first find Orion, which is in the south in early evening. Sirius, the brightest star in the night sky, is below Orion, with fainter Procyon farther to the lower left. The unicorn fills the space between these bright lights.

Until the 17th century, European skywatchers largely ignored the area to the east of Orion. And it’s hard to blame them — that expanse of sky looks pretty empty.

By the early 1600s, though, things were changing. For one thing, European powers were exploring the world’s oceans, so navigators began producing more detailed maps of the sky. And for another, as astronomers turned their early telescopes toward the sky, they found that many “empty” regions were actually filled with amazing sights.

So 400 years ago, a new constellation was created to encompass a dark area near Orion: Monoceros, the unicorn. It’s still not much to look at with the eye alone. But a telescope reveals a triple-star system, a star that staged a big outburst, and much more.

Perhaps the most famous of the unicorn’s wonders is the Rosette Nebula, a giant cloud of gas and dust that surrounds a cluster of young stars. Through a telescope, it looks like a faint smudge of light. But in photographs, it looks like an orange or pink rose — a beautiful decoration for a faint unicorn.

To find the unicorn, first find Orion, which wheels across the south in early evening. Sirius, the brightest star in the night sky, is below Orion, with fainter Procyon farther to the hunter’s lower left. The unicorn fills the space between these bright lights — a region of the sky that’s best appreciated with a telescope.

We’ll have more about the unicorn tomorrow.
 

Script by Damond Benningfield

The constellation Puppis scoots low across the south on winter evenings. It is below Sirius, the brightest star in the night sky. Puppis represents the deck at the back of the Argo, the ship that carried Jason and the Argonauts.

The world’s largest search for ET has added more “ears” to the project. It’s using MeerKAT — an array of 64 radio telescopes in South Africa. The array can scan much more of the sky than the project’s current instruments. That allows it to listen in on many more stars.

Breakthrough Listen has been operating for three years. It uses giant radio dishes in the United States and Australia, plus a few smaller ones.

The telescopes listen for radio signals produced by civilizations in other star systems. They’re not sensitive enough to pick up routine radio broadcasts. But they could detect high-powered radar beams or similar signals. The goal is to scan a million or more nearby star systems, plus a few more-distant targets.

The project has detected a few interesting signals. But detailed study has revealed that almost all of them are either interference from radio sources on Earth, or they’re produced by stars or other astronomical objects.

MeerKAT will expand the project’s reach. It can monitor up to 64 target stars at a time, and should be sensitive to signals within about 250 light-years. Breakthrough Listen will piggyback off the work of other projects, so it’ll operate any time the telescopes are aiming at the sky.

One of the first targets is Proxima Centauri, our closest neighboring star system, about four light-years away. At least two planets orbit the star, and there could be more — potential homes for ET.
 

Script by Damond Benningfield

The Moon backlights the IceCube neutrino observatory at the south pole. The observatory uses special detectors buried deep in the ice to catch the ghostly particles known as neutrinos, which are produced in the hearts of stars, in stellar explosions, around black holes, and in other energetic locations. The Antarctic ice filters out other particles, ensuring that scientists are detecting only the neutrinos. IceCube is being upgraded to make it more sensitive to the particles. [Raffaela Busse/IceCube/NSF]

Faint Camelopardalis, the giraffe, is high in the north during the evening hours, but you need help to find it. It stands between the conspicuous stars Polaris, the pole star, and Capella, a bright yellow star in the constellation Auriga.

Scientists are drilling deep into the ice at the south pole to learn more about some of the most elusive particles in the universe. They’ve been operating a huge observatory there for more than a decade. And they’re about to wrap up a big upgrade.

IceCube is looking for evidence of neutrinos. Stars and other objects produce huge numbers of them, and send them streaming into space at almost the speed of light. In fact, billions of neutrinos pass through every square inch of your body every second. Yet they almost never interact with other matter.

The only time they do is when they smash head on into the nucleus of an atom. That produces a flash of blue light.

IceCube uses more than 5,000 detectors buried a mile or more deep in the ice to look for those flashes. The ice blocks other types of particles and radiation, so any flashes should come from neutrinos. Scientists can trace the direction and brightness of the flashes to track their origin, and to learn something about what produced the neutrinos. That’s provided details about supermassive black holes and other sources.

The upgrade is adding about 750 detectors, which are more sensitive than the older ones. That should improve the sensitivity of IceCube by 25 percent or more.

Work is supposed to wrap up in the next few weeks — helping scientists catch a few more ghostly neutrinos.

We’ll talk about another big telescope upgrade tomorrow.
 

Script by Damond Benningfield

A full Moon lights up this mid-winter night. On snowy ground, it adds a silvery glow to the landscape. In fact, the full Moon of February is known as the Snow Moon. And because there wasn’t much to eat at this time of year, some cultures also called it the Hunger Moon.

Every full Moon has its own name. Almost all of them are based on the traits of the time of year. So during summer, we get names like Strawberry or Corn Moon. And during fall, we have the Harvest and Hunter’s Moons.

Most of those names come from a couple of sources. One is the British Isles, from Celtic and Old English. The other is from the native cultures of North America — in particular, the Algonquin of New England.

Many of the names also applied to the months of the year. According to some sources, for example, in Old English, February was the mud month. That was either because of the messy weather, or because people made cakes for the gods that looked like they were made of mud.

The American names were popularized in the early 1900s. A book for the Boy Scouts listed many Algonquin names. And later, the names became a regular feature of the Farmer’s Almanac.

So enjoy the Snow Moon as it casts its cold light across a cold winter’s night. And it has a bright companion: Regulus, the heart of the lion. It rises below the Moon. Regulus will rise closer to the right of the Moon tomorrow night.

Script by Damond Benningfield

A full Moon lights up this mid-winter night. On snowy ground, it adds a silvery glow to the landscape. It has a bright companion: Regulus, the heart of the lion, which rises below the Moon. Regulus will rise closer to the right of the Moon tomorrow night.

The glare of the full Moon overpowers most of the stars around it. Only the brightest of stars shine through. And that’s what we have tonight. Three bright stars form a wide triangle, with the Moon along one side of it.

The star that appears closest to the Moon is Pollux, the brighter of the twins of Gemini. It’s above the Moon at nightfall. It’s a stellar giant — it’s much bigger and brighter than the Sun. It’s well past the prime of life, so it’s puffed up to giant proportions. And it’s only about 34 light-years away. The combination of size and distance makes it bright and easy to spot.

The next-closest companion star is Regulus, the leading light of Leo, the lion. It climbs into good view below the Moon by about 8 o’clock.

Regulus is a binary — two stars locked in a tight orbit around each other. The main star is much brighter and more massive than the Sun. Its companion is a white dwarf — the small, faint, dead core of a star. The system is about 80 light-years away.

The final companion is Procyon, which is well to the right of the Moon. It’s the brightest star of the little dog, so it’s known as the Little Dog Star. It, too, is a binary. And like Regulus, it consists of a star in the prime of life paired with a white dwarf. The system is among our closest neighbors — only about 11 light-years away.

Look for this trio of bright stars shining through the brilliant moonlight all night long.

Script by Damond Benningfield

Three bright stars form a triangle that shines through the light of the full Moon tonight. Pollux, a twin of Gemini, is above the Moon at nightfall. Regulus, the heart of Leo, climbs into view below the Moon by about 8 p.m. Procyon is well to the right of the Moon.

The star Castor represents one of the twins of Gemini. But it takes the business of “twinhood” to extremes. Although we see it as a single point of light, Castor actually consists of three sets of stellar twins — a total of six stars in all.

All six of them really are related. They were born from a single giant cloud of gas and dust, probably a few hundred million years ago.

Two sets of Castor’s twins are more fraternal than identical. One star in each pair is a good bit bigger, brighter, and heavier than the Sun. The other is smaller, fainter, and less massive than the Sun.

The stars in these pairs are so close together that they orbit each other in just a few days. At such close range, there’s no way for telescopes to see them as individual stars. Instead, special instruments separate the “barcodes” of the stars as they go around each other, providing details on each star.

The stars in the third pair of Castor’s twins are identical. Each star is smaller, cooler, and less massive than the Sun, and much fainter. And while the other two sets of twins are fairly close to each other, this pair is a long way away. It takes thousands of years for it to orbit the others — a set of twins that keeps its distance from its brighter siblings.

The twins of Gemini are in the east at nightfall, near the Moon. The brighter twin, Pollux, is above the Moon, with Castor about the same distance to the upper left of Pollux.

Script by Damond Benningfield

The twins of Gemini are in the east at nightfall, near the Moon. The brighter twin, Pollux, is above the Moon. Castor, which is a system of six stars, is about the same distance to the upper left of Pollux.

Punxsutawney Phil carries a heavy load on his little shoulders. According to folklore, if the groundhog pops out of his burrow and sees his shadow today, there will be six more weeks of winter. If there’s no shadow, it means an early spring.

Phil has become the unofficial groundhog of Groundhog Day. He’s near the small town of Punxsutawney, Pennsylvania. His appearance is part of a day-long festival that’s been celebrated since 1887. Many other towns hold similar fetes.

There actually is a bit of truth to the legends. Crisp, sunny days often follow cold fronts — part of a pattern of continuing cold weather. Cloudy skies can be produced by warmer air pushing up from the south — perhaps the start of more spring-like patterns.

Groundhog Day is one of several commemorations of a cross-quarter day. Such days occur about half way between a solstice and an equinox. In many cultures, a cross-quarter day represented the beginning of a new season, not its middle.

In the British Isles, there were several celebrations of the February cross-quarter day. In Ireland, it began as Imbolg, which honored the goddess Brigid. Later, Christians celebrated it as Saint Brigid’s Day, honoring Ireland’s patron saint. And in other regions, it was Candlemas. People had their candles blessed by a priest, then used them to light up the rest of the year.

So keep an eye on your own skies to see if spring is nigh — or winter will maintain its icy grip.

Script by Damond Benningfield

Today is Groundhog Day, which is one of several commemorations of a cross-quarter day. Such days occur about half way between a solstice and an equinox. In many cultures, a cross-quarter day represented the beginning of a new season, not its middle.

Look toward the northeast this evening for the Big Dipper. Its handle points toward the horizon. The second star from the end of the handle is Mizar. If you look at it under dark skies, you should see a faint star very near Mizar, called Alcor.

If you want to scoop up a lot of gold, just hang around a close pair of neutron stars. If the stars spiral together, they can produce amazing amounts of gold, silver, and other heavy elements. In fact, a merger that was seen in late 2021 produced enough to make a thousand planets as massive as Earth.

A neutron star is the tiny, ultra-dense corpse of a once-mighty star. At the end of its life, the core of such a massive star collapses. The star’s outer layers then explode as a supernova.

In December of 2021, astronomers saw the merger of two neutron stars. The stars were in a galaxy more than a billion light-years away. That was close enough to study the event in detail.

It began with a gamma-ray burst — an extremely powerful outburst of energy. It shined far brighter than the combined light of many galaxies of stars. The outburst lasted for less than a minute. That length suggested the outburst was powered by the collapse of a massive star.

But detailed analysis proved otherwise. The event was the result of the merger of two neutron stars. Much of their material splattered out into space. Temperatures were so extreme that atoms slammed together to make heavier elements — including gold and silver. The remnants of the two stars then merged to make a black hole. But many of the heavy elements escaped. Some of them may since have been incorporated into new planets — perhaps to adorn the people of future civilizations.

Script by Damond Benningfield

The Moon is especially close to a star with a dangerous-sounding name tonight: El Nath, “the butting one.” It marks the tip of one of the horns of Taurus. It’s the bull’s second-brightest star.

El Nath is most famous for its location. It’s the closest bright star to the galactic “anticenter” — the point directly opposite the heart of the Milky Way Galaxy. So when we look in that direction, we’re looking toward the galaxy’s rim. El Nath isn’t on the rim, though. It’s about 135 light-years away, while the rim is more than 20,000 light-years farther.

El Nath is interesting for more than just its direction, though. It’s a stellar giant. It’s about five times the mass of the Sun, so even though it’s only a couple of percent the Sun’s age, it’s already past the prime of life. It’s puffed up to several times the Sun’s diameter, and it’s much hotter than the Sun. The combination makes it about 700 times brighter than the Sun.

Over the next few million years, El Nath will get even bigger and brighter. Then it will cast its outer layers into space, leaving only its hot but dense core — and the bull will lose his impressive horn.

El Nath is close to the left or lower left of the bright gibbous Moon at nightfall. Two brighter lights are in the opposite direction. Mars and Aldebaran stand to the upper right of the Moon. Mars is the brighter of the two orange lights, and stands a little higher in the sky.

Script by Damond Benningfield

The Moon is especially close to a star with a dangerous-sounding name tonight: El Nath, “the butting one.” It marks the tip of one of the horns of Taurus. It’s the bull’s second-brightest star.

Mars and the Moon will play hide-and-seek for much of the year. The Moon will pass in front of the Red Planet four times, briefly hiding it from view. From the U.S., the best of those events takes place tonight. Mars will disappear from view from Florida across Texas to southern California.

Mars and the Moon will play hide-and-seek for much of the year. The Moon will pass in front of the Red Planet four times, briefly hiding it from view. From the United States, the best of those events takes place tonight. Mars will disappear from view from Florida across Texas to southern California.

Such an event is called an occultation. That’s from a Latin word that means “to hide.” Occultations are possible because the orbits of both Mars and the Moon lie near the ecliptic, which is the Sun’s path across the sky. Both bodies wander away from the ecliptic a little, though, so most months the Moon passes within a few degrees of Mars but doesn’t cover it up.

Even when the two bodies do line up, though, it’s visible from limited regions. In part, that’s because an occultation lasts only an hour or two, so from most of Earth it happens when Mars and the Moon are below the horizon. And the Moon is much closer to us than Mars is, so most regions see the Moon pass above or below Mars — with no occultation at all.

Tonight, though, the geometry will be just right from the southern United States. The Moon will cover Mars before midnight, and the Red Planet will remain hidden for up to a couple of hours.

The rest of the country will miss out on the occultation, but will still see a beautiful sight. Mars looks like a brilliant orange star quite near the Moon throughout the night.

More about the Moon and Mars tomorrow.

One of the biggest and brightest of the geometric figures in the night sky is the Winter Circle or Hexagon — a ring of seven bright stars, with Betelgeuse, the orange shoulder of Orion, as its hub. The figure is in the east and southeast as night falls.

For fans of geometric shapes, the night sky is a paradise. You can connect the bright stars to make just about any shape you can think of: triangles, squares, rectangles, parallelograms, and many more.

One of the biggest and brightest of these figures is the Winter Circle or Hexagon — seven bright stars, with one more as its hub. It’s in the east and southeast as night falls now.

Its hub is Betelgeuse, the orange shoulder of Orion. It’s about halfway up the sky at nightfall, in the east-southeast. To see the circle, drop the lower right of Betelgeuse until you come to Sirius, the brightest star in the night sky. It’s in the big dog, so it’s also known as the Dog Star.

Using Betelgeuse as the center of your clock, sweep clockwise to Procyon. It is the brightest star of the little dog, so it’s known as the Little Dog Star.

Next up, in the east, are Pollux and Castor, the twins of Gemini. Capella, in Auriga the charioteer, is high above them. Then go to the right for Aldebaran, the eye of the bull. Right now, the planet Mars is close by, so it adds one more point to the circle.

Then it’s down to Rigel, Orion’s bright blue-white foot, and back to Sirius to complete the shape.

This is a good time to view this giant figure. The glare of the gibbous Moon overpowers most of the stars, but the bright lights of the Winter Circle shine through — a beautiful bit of celestial geometry for winter nights.

Script by Damond Benningfield

The planet Mercury is in view in the early morning now. It’s farthest from the Sun in our sky, so it will hang around for a few days. It is in the southeast at first light, and looks like a bright star, although it’s so low that you need a clear horizon to spot it.

The surface of Mercury is crawling with snakes — more than two dozen of them. The largest is more than 165 miles long. You don’t need to worry about their bite, though — they’re remnants of ancient volcanoes.

The features are known as faculae — a Latin word that means “little torches.” They’re patches of bright material around dead volcanoes. The volcanoes erupted billions of years ago, when Mercury was young. They blasted out huge amounts of lava that contained a lot of water and similar compounds.

Planetary scientists have selected different themes for naming the surface features on Mercury and the other planets. Mercury’s faculae have been named for the words for “snake” in different languages. Some of the features look like snakes, and the god Mercury often was depicted with a snake on the end of his staff.

The largest snake is Nathair Facula, from the Irish word for snake. It’s about 165 miles in diameter. Other names include Inyoka, from the Zulu word for snake; Ular, from Malaysia; Abeeso, from Somalia; and Orm, from Sweden.

Not all faculae have been named yet. So we can look forward to more snakes wriggling across Mercury in the years ahead.

Mercury is in good view in the early morning now. It’s farthest from the Sun in our sky, so it’ll hang around for a few days. It’s in the southeast at first light, and looks like a bright star. But it’s so low that you need a clear horizon to spot it.

Script by Damond Benningfield

Jupiter is the beachball of the solar system: big, round, and painted with colorful stripes. It’s also the largest planet in the solar system, so each stripe is thousands of miles wide.

The stripes are created by Jupiter’s high-speed rotation — it spins on its axis once every 10 hours. They’re separated by jet streams that blow at hundreds of miles per hour and dip a couple of thousand miles into the atmosphere. And their borders can be turbulent, marked by ripples and waves as big as countries.

The bands alternate between light-colored zones and darker belts. The clouds in the zones are higher, while those in the belts are lower, allowing us to see deeper into Jupiter’s atmosphere. The clouds are made of ammonia and other compounds, with clouds of water below.

The bands are colored in shades of yellow, red, and brown, giving Jupiter its beachball appearance. The color may come from compounds of sulfur, phosphorus, and other elements dredged from deep below.

Giant storms float through the bands. The biggest is the Great Red Spot, which is the size of Earth — a colorful decoration for a colorful beachball.

Look for Jupiter to the upper left of the Moon this evening. It looks like a brilliant star — only the Moon and the planet Venus outshine it. And if you can’t catch them tonight, Jupiter and the Moon will be about the same distance apart tomorrow night, with Jupiter to the right of the Moon.
 

Script by Damond Benningfield

Look for the planet Jupiter to the upper left of the Moon this evening. It looks like a brilliant star. If you can’t catch them tonight, Jupiter and the Moon will be about the same distance apart tomorrow night, with Jupiter to the right of the Moon.

The Sun’s two closest planets are snuggling close to each other. They’re quite low in the southwest at sunset. But they’re both bright, so if you time it right, you should be able to pick them out.

Venus is lower but brighter — the “evening star.” Fainter Mercury is a little above it. Mercury is the Sun’s closest and smallest planet, with Venus the next one out.

Mercury has no atmosphere to speak of. So with no wind or rain, any changes on its surface have to come from inside the little planet, or from impacts by objects beyond Mercury.

A recent study found that the surface changes much more often than expected. And most of the changes are driven from within.

Scientists compared more than 58,000 pairs of images from the Messenger spacecraft, which orbited Mercury from 2011 to 2015. It snapped pictures of the same regions of the planet at different times. By comparing those images, scientists found 20 changes to the surface.

One of them was an impact crater — a hole gouged by a collision with a space rock. But the others probably were caused by processes inside Mercury itself. They all appeared in regions that are associated with volcanic activity. So the features probably were created by quakes, the motions of molten rock, or other internal activities. The number of new features suggests that Mercury’s surface changes a lot — driven from inside the Sun’s smallest planet.
 

Script by Damond Benningfield

Venus and Mercury, the Sun’s two closest planets, are snuggling close to each other, quite low in the southwest at sunset. But they’re both bright, so if you time it right, you should be able to pick them out. Venus is lower but brighter — the Evening Star.

Jean-Dominique Cassini probably taught us more about the planet Saturn than anyone else before or since. 350 years ago this month, he discovered its second-largest moon. It’s a giant “dirty snowball” — a mixture of ice and rock.

Cassini was a leading astronomer not only of his era, but of any era. He was born in Genoa, but later became a citizen of France, where he did most of his work. He studied Jupiter, the Moon, the speed of light, and much more. But he’s best known for his observations of Saturn.

He discovered a dark “gap” in Saturn’s rings. It’s named the Cassini Division in his honor. He also discovered four moons — one of them on December 23rd, 1672. Much later, it was named for the goddess Rhea, the wife of Kronos, the Greek equivalent of Saturn.

The moon is 950 miles in diameter — less than half the size of our own moon. It orbits Saturn once every four and a half days.

Most of what we know about Rhea came from the Cassini spacecraft — named for Jean-Dominique. It flew as close as about 40 miles from the moon. It showed that Rhea is about 75 percent ice and 25 percent rock. Its surface has two giant impact basins, plus some tall ice cliffs — the surface of a moon that was discovered 350 years ago.

Saturn is easy to find tonight because it’s quite close to our moon. It looks like a bright star to the right of the Moon at nightfall. But you need a telescope to see Rhea.
 

Script by Damond Benningfield

Saturn, the second-largest planet in the solar system, is easy to find tonight because it’s quite close to the Moon. It looks like a bright star to the right of the Moon at nightfall.

Venus, the Evening Star, is quite low in the southwest at sunset, well to the lower right of the crescent Moon. The fainter planet Mercury is a little above Venus.

One of the most remarkable scientific developments of the last couple of decades is the idea that life could exist elsewhere in our own solar system. Quite a few worlds are thought to have possible habitats: Mars, some of the moons of the giant outer planets, and the dwarf planets Pluto and Ceres. Even the planet Venus has been added to the list.

Venus would appear to be as unlikely a home for life as you could ever imagine. Its atmosphere is extremely hot, dense, and toxic. And it’s topped by clouds of sulfuric acid. Yet a few observations have hinted that microscopic life could inhabit those clouds.

Some observations have shown dark “mats” inside the clouds — a possible signature of bacteria. And a couple of years ago, a team reported evidence of phosphine in the clouds. Here on Earth, phosphine is a byproduct of life.

Follow-up work by other groups, though, discounts that possibility. The most recent is a study using SOFIA — an airborne observatory. It scanned Venus’s clouds in November of 2021. And it found no evidence of phosphine. In fact, scientists say there couldn’t be more than about one part per billion.

Even so, few are ready to give up on the possibility of life in the clouds of this inhospitable world.

Venus is the “evening star.” It’s quite low in the southwest at sunset, well to the lower right of the crescent Moon. The fainter planet Mercury is a little above Venus.
 

Script by Damond Benningfield

The Moon and all five planets visible to the naked eye are in view in the evening twilight. The Moon, Venus, and Mercury form a tight triangle low in the southwest. Saturn is well to their upper left, with Jupiter farther along that line. Orange Mars is in the east.

The early evening sky serves up an amazing gift for this Christmas Eve: All five planets that are visible to the unaided eye are in view at the same time. And a thin crescent Moon adds a ribbon to the package.

Shortly after sunset, the Moon and the planets Venus and Mercury form a tight triangle quite low in the southwest. You’ll need a clear horizon to spot them, but it’s worth the effort. The view is a little better from locations that are farther south.

Venus is the “evening star” — the brightest object in the night sky after the Moon. Mercury is between the Moon and Venus and slightly higher. It’s fainter than Venus, but its proximity to the brighter objects will help it stand out.

Arc to the upper left and you’ll come to Saturn, the second-largest planet. It, too, looks like a bright star. And brighter Jupiter, the largest planet, stands due south, fairly high in the sky.

Continue the arc far to the lower left and you’ll come to planet number five, Mars. It’s beginning to fade from its peak early in the month, but it’s still unmistakable. It looks like a very bright orange star. A true star is close to its lower right: Aldebaran, the orange eye of the bull.

And Orion, one of the most beautiful of all constellations, is below them, quite low in the east. It will climb high across the south later on — more beauty in the night sky — a gift every single night of the year.

More about the evening sky tomorrow.
 

Script by Damond Benningfield

Cygnus, the swan, is about a third of the way up the western sky at nightfall. One of its wonders is Minkowski’s Footprint, which is a dying star that is surrounding itself with a cloud of gas. You need a telescope to see it.

A star that’s at the beginning of its final act is going out in style. It’s blowing hot gas off its surface, forming clouds on either side of the star. Powerful winds from the star are sculpting both clouds into cones, with the wide ends closer to the star.

The star doesn’t have a name — only a long list of numbers. But the entire complex is nicknamed Minkowski’s Footprint, after the astronomer who cataloged it, and its resemblance to a footprint in some images.

The star is bigger, brighter, and more massive than the Sun. But it’s burned through the nuclear fuel in its core, so the fusion reactions that power it are shutting down. That’s causing the star’s outer layers to surge out into space, creating a nebula around the star.

This process is in its early days, so it’s known as a protoplanetary nebula. The nebula is visible only because its gas and dust reflect light from the star. But in a few thousand years, the dying core will become much hotter. Its radiation will cause the clouds to glow on their own, creating a full-fledged planetary nebula.

The expelled material will continue to expand, forming a colorful bubble. After tens of thousands of years, it’ll fade from view, and only the hot but dead core will remain — the end of a star.

The nebula is near the beak of Cygnus, the swan, which is about a third of the way up the western sky at nightfall. But you need a telescope to see this dying star.
 

Script by Damond Benningfield

The most-distant object that’s readily visible to the eye alone stands directly overhead at nightfall now, in the constellation Andromeda. Under dark skies, M31 looks like a tiny cloud. But it’s really a giant spiral galaxy — about 2.5 million light-years away.

The most-distant object that’s readily visible to the eye alone stands directly overhead at nightfall now, in the constellation Andromeda. Under dark skies, M31 looks like a tiny cloud. But it’s really a giant spiral galaxy much like our own — about two and a half million light-years away.

It’s the closest of all big galaxies, so it’s a popular target for astronomers. And one team recently found what may be a mid-sized black hole in its outskirts.

The black hole is in a star cluster that’s about six million times the mass of the Sun. It’s been classified as a globular cluster — a tightly packed ball of stars as old as the galaxy itself.

The new study used telescopes on the ground and in space. Their observations showed that the cluster’s light tapers off in an odd way. The stars at its center appear to be orbiting something that’s small but massive. And the cluster isn’t as old as the galaxy. From that, the astronomers concluded that a rare mid-sized black hole inhabits the cluster’s heart. It’s about a hundred thousand times the mass of the Sun.

The cluster probably began as the core of a smaller galaxy. As the galaxy passed near M31, its outer precincts were pulled away by M31’s more powerful gravity. The stars in those regions merged with M31. The core stuck together and entered orbit around the larger galaxy. And that’s where it is today — the remnant of a dead galaxy with a black hole in its heart.
 

Script by Damond Benningfield

Today is the winter solstice — the shortest day and longest night of the year in the northern hemisphere. The Sun stands farthest south for the entire year, too, so it scoots low across the horizon.

For centuries, people in regions as far flung as China, Persia, and the Americas celebrated this astronomical event. It marked a turning point in the year — offering a future of longer, warmer days.

In ancient Rome, the solstice was celebrated with the most popular holiday of the year, Saturnalia. It honored Saturn, a god of agriculture. It grew out of older rituals that were tied to the winter planting season. Romans from all walks of life enjoyed a week-long festival. It featured music, feasting, gift giving, and decorating with greenery.

Early Christians celebrated the feast of Saint Lucy, who’s remembered for helping persecuted Christians who were in hiding. In legend, she wore a wreath of candles on her head to light the way while leaving her hands free.

If much of this sounds familiar, there’s good reason. Many of these ancient traditions live on in the modern celebration of Christmas — no longer linked to harvesting and planting, but still bringing light and festivity into the darkest season of the year.

And Julius Caesar added to the celebration when he reformed the calendar, in 46 BC. He placed the beginning of the year shortly after the solstice — on the first of January — where it remains today.
 

Script by Laura Tuma

Today is the winter solstice, the shortest day of the year in the northern hemisphere. For centuries, people in regions as far flung as China, Persia, and the Americas celebrated the date. It marked a turning point in the year, offering a future of longer, warmer days.

Shortly after noon the next couple of days, a dagger of sunlight will slide across a bluff on the banks of the Concho River at Paint Rock, Texas. As the Sun stands highest in the sky, the dagger will stab through the heart of a several-hundred-year-old pictograph.

The red painting depicts a shield — a possible symbol for the Sun. The dagger of sunlight crosses the shield only around the winter solstice, which is coming up tomorrow. It’s the shortest day of the year in the northern hemisphere, when the Sun stands farthest south in the sky.

The Paint Rock site contains hundreds of pictographs, which extend about half a mile along the bluff. Some of the pictures clearly depict the Sun.

A couple of decades ago, the site owners heard about other rock-art sites with alignments to the solstices or equinoxes. They contacted a University of Texas astronomer, who suggested they watch the site at local noon on these dates.

On the winter solstice of 1996, they discovered the dagger of sunlight crossing the shield. Later study confirmed that the alignment probably was intentional — the shaft of light shines through a crack in the rocks only at the solstice.

Native cultures may have painted the symbol to indicate the solstice. If so, then they probably held rituals on the solstice to confirm the power of the rulers, and to entice the Sun northward — bringing warmth back to the Texas hills.

More about the solstice tomorrow.
 

Script by Damond Benningfield

Tomorrow is the winter solstice, which marks the beginning of winter in the northern hemisphere. It is the shortest day and longest night of the year. The Sun stands farthest south in the sky for the year as well.

The solar system is undergoing a population explosion. It’s not adding new members — they’ve been here all along. But astronomers are finding more of them.

Almost all of the newly counted are small chunks of rock and ice. Most are in the asteroid belt — a band of rocky debris between Mars and Jupiter. Astronomers are actually searching for bodies that come close to Earth — potential threats to our planet. But they also catch asteroids that are farther away. So they typically discover thousands of them every month.

They also discover asteroids that are inside Earth’s orbit. Three new ones were announced in October. One of them is the closest asteroid to the Sun yet seen. The orbit of another one crosses ours, so it could someday threaten our planet. The object is about a mile wide, so any impact would be catastrophic.

We won’t have that problem with another recent set of discoveries.

A year ago, astronomers reported more than 450 new objects in the Kuiper Belt — a region beyond the orbit of Neptune, the Sun’s most remote major planet. Some of them follow orbits that average more than 200 times Earth’s distance from the Sun.

The orbits of some of them may be influenced by the gravity of Planet Nine — a suspected giant world deep in the Kuiper Belt. So scientists are studying the orbits to help track down the elusive planet — perhaps adding one more body to the solar system’s growing population.
 

Script by Damond Benningfield

Cygnus, the swan, is in the west on December evenings. Its beak points downward, with its wings roughly parallel to the horizon, as though it’s plunging groundward. This angle earned the constellation a nickname: the Northern Cross.

When most people look at the glass plates preserved at Harvard College Observatory, they see black dots, smears, and smudges. Astronomers see a chance to learn how the stars, galaxies, and clouds those markings represent have changed over the past century or longer. And artists see the beauty of the universe and the hard work of the women who analyzed the plates.

The original plates are negatives — they show the stars in black and the background sky in white. At Harvard, women “computers” marked and labeled the astronomical objects in the images. They also measured the brightness of those objects and made many other notations.

The plates have been scanned to make it easier for astronomers to find them. As part of that process, the hand-made notations were erased, although all of the plates were photographed first, and some of the originals have been preserved.

To commemorate the work of the women computers, artist Erika Blumenfeld created “Tracing Luminaries.” It’s a set of six prints. She erased the stars, leaving only the written notations, which were hand-layered with 24-karat gold.

Lia Halloran interpreted the plates themselves in “Your Body is a Space that Sees.” It’s a series of prints depicting comets, galaxies, and other objects. The titles include the names of the women computers, including Henrietta Leavitt and Annie Jump Cannon — two of the most important astronomers of the 20th century.
 

Script by Damond Benningfield

Hercules is low in the west at nightfall. A bright nova, which is an outburst from a white dwarf star, flared to life in the constellation in 1934. The nova may have helped inspire the origin story of Superman, who debuted four years later.

Virgo is a popular location for exoplanets, including the first ones ever confirmed. There’s no special reason for it, except perhaps for the size of the constellation — it’s the largest member of the zodiac.

Virgo is easy to find in the wee hours of tomorrow because the Moon passes near Spica, its brightest star.

As far as we know, Spica doesn’t have planets of its own. And if it does, they’re doomed, because the system’s main star will explode as a supernova in a few million years.

There’s no reason an exploded star couldn’t acquire planets after its demise, though. In fact, that may be the case for the first exoplanets ever discovered. They orbit a pulsar — the ultra-dense corpse of a supernova.