StarDate
909 episodes - English - Latest episode: 2 days ago - ★★★★★ - 205 ratingsStarDate, the longest-running national radio science feature in the U.S., tells listeners what to look for in the night sky.
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Episodes
Dead Stars
March 19, 2023 05:00 - 2 minutes - 1.03 MBVulpecula, 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 mass...
Vulpecula
March 18, 2023 05:00 - 2 minutes - 1.03 MBVulpecula, 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...
Declining Birth Rate
March 17, 2023 05:00 - 2 minutes - 1.03 MBOur 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 th...
Solar Rain
March 16, 2023 05:00 - 2 minutes - 1.03 MBBig 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...
Messier 3
March 15, 2023 05:00 - 2 minutes - 1.03 MBA 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 ...
A New Twist
March 14, 2023 05:00 - 2 minutes - 1.03 MBAstronomers 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...
Galactic Fossils
March 13, 2023 05:00 - 2 minutes - 1.03 MBGreen 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 fa...
Daylight Saving Time
March 11, 2023 06:00 - 2 minutes - 1.03 MBIt’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-hou...
Orion Sieve
March 10, 2023 06:00 - 2 minutes - 1.02 MBThe 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 bu...
Active Mars
March 08, 2023 06:00 - 2 minutes - 1.02 MBMars 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...
Comet Kohoutek
March 07, 2023 06:00 - 2 minutes - 1.02 MBComets 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...
Early Galaxies
March 06, 2023 06:00 - 2 minutes - 1.02 MBJames 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 sm...
Future Fireworks
March 04, 2023 06:00 - 2 minutes - 1.02 MBIf 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 a...
Following Up
March 03, 2023 06:00 - 2 minutes - 1.02 MBAstronomers 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 so...
More Venus and Jupiter
March 01, 2023 06:00 - 2 minutes - 1.02 MBIf 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 an...
Venus and Jupiter
February 28, 2023 06:00 - 2 minutes - 1.06 MBThe 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 bri...
Water Worlds
February 27, 2023 06:00 - 2 minutes - 1.06 MBWith 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 ty...
Running Away
February 26, 2023 06:00 - 2 minutes - 1.06 MBFamilies 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 abou...
Columba
February 25, 2023 06:00 - 2 minutes - 1.06 MBA 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...
Keeping it Going
February 24, 2023 06:00 - 2 minutes - 1.06 MBFor 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...
Moon, Venus, Jupiter III
February 23, 2023 06:00 - 2 minutes - 1.06 MBThe 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. Astronau...
More Moon, Venus, Jupiter
February 22, 2023 06:00 - 2 minutes - 1.06 MBThe 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 o...
Moon, Venus, Jupiter
February 21, 2023 06:00 - 2 minutes - 1.06 MBThe 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 ...
Iron
February 20, 2023 06:00 - 2 minutes - 1.03 MBIron 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...
Alpheratz
February 19, 2023 06:00 - 2 minutes - 1.03 MBThere’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 plane...
Procyon
February 18, 2023 06:00 - 2 minutes - 1.03 MBExtra 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 i...
Megatsunami
February 17, 2023 06:00 - 2 minutes - 1.03 MB3.4 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 findin...
Stormy Skies
February 16, 2023 06:00 - 2 minutes - 1.03 MBStorms 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 d...
Vaporizing Satellites
February 15, 2023 06:00 - 2 minutes - 1.03 MBIn 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 sp...
Fritz Zwicky
February 14, 2023 06:00 - 2 minutes - 1.03 MBGrowing 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...
Dark Matter
February 13, 2023 06:00 - 2 minutes - 1.03 MBThe 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, t...
Close Black Hole
February 12, 2023 06:00 - 2 minutes - 1.03 MBBlack 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 —...
Menkar
November 20, 2022 06:00 - 2 minutes - 1.02 MBA star that’s about to undergo some big changes highlights the head of Cetus, the whale or sea monster. It probably will become unstable, then blow its outer layers into space to form a colorful bubble. Menkar — from an Arabic name that means “the nostril” — is low in the east at nightfall and high in the south around midnight. It’s the second-brightest star in the constellation, and the brightest in the character’s head. Menkar is classified as a red giant. It’s far beyond the prime of li...
Northern Fly
November 19, 2022 06:00 - 2 minutes - 1.02 MBFor three centuries, an insect buzzed around the backside of Aries. But the ram got rid of the pest a century ago, claiming the stars as its own. The buzzer was created in 1612, by Dutch astronomer Petrus Plancius. He took some faint stars from an empty region near Aries. He named his new constellation Apis — Latin for “bee.” But there was already a celestial bee. So in 1687, German astronomer Johannes Hevelius renamed Apis. He called it Musca — the fly. And in 1822, it was adjusted to Mus...
Patrick Blackett
November 18, 2022 06:00 - 2 minutes - 1.02 MBCosmic rays are handy things for scientists. They tell us about some of the most powerful and dramatic events in the universe. They reveal details about the structure of matter. And for British scientist Patrick Blackett, they led to the 1948 Nobel Prize in Physics. Blackett was born 125 years ago today. He enrolled in a naval academy at age 13. He served in the Royal Navy during World War I and saw combat in a couple of campaigns. After the war, he decided to study physics. In particular, ...
Z Camelopardalis
November 17, 2022 06:00 - 2 minutes - 1.02 MBOnce every few weeks, the star system Z Camelopardalis pops off. It flares to about 50 times its normal brightness, then slowly fades. But at least once in the last couple of thousand years, it probably flared thousands of times brighter than its normal outbursts — like the difference between a flashlight and a searchlight. And today, astronomers can still see the residue of that blast. The system is in Camelopardalis, the giraffe. The constellation is about half way up the north-northeaste...
Deep Companion
November 14, 2022 06:00 - 2 minutes - 1.02 MBThe asteroid that killed the dinosaurs might have had some help. A crater discovered off the coast of Africa formed at about the same time as the one gouged by the dinosaur killer. That suggests they could have been companions — perhaps formed by pieces of a larger asteroid. Much of the life on Earth died when a miles-wide space rock slammed into our planet 66 million years ago. The impact formed a crater in the Gulf of Mexico. Known as Chicxulub, it’s more than a hundred miles wide. Debris...
The Sea Monster
November 13, 2022 06:00 - 2 minutes - 1.02 MBMany of the myths of ancient Greece sound like they were written for Hollywood. There’s beauty, mystery, and treachery, with enough nasty monsters to occupy hordes of computer animators. One of the nastiest is Cetus, the sea monster, which crawls across the southern sky on November evenings. His story begins with Cassiopeia, the queen of Ethiopia. She was beautiful but vain — she bragged that she was the most beautiful of all. That didn’t sit well with the sea nymphs, who were also great be...
Hamlet’s Supernova?
November 12, 2022 06:00 - 2 minutes - 1.02 MBCassiopeia the queen stands high in the northeast at nightfall. Some of her stars form a giant letter M or W. 450 years ago this week, a brilliant new star appeared near the center point of that letter. Today, it’s known as Tycho’s Supernova, for Tycho Brahe, who published an extensive study of it. But it might also be called Hamlet’s Supernova. A study a few years ago suggested the star might have inspired William Shakespeare to write the famous play. The star appeared in 1572, when Shake...
Tycho’s Supernova
November 11, 2022 06:00 - 2 minutes - 1.02 MBTycho Brahe was one of the greatest observers of the night sky. In the era before telescopes, he compiled some of the most accurate star catalogs in history. It didn’t take a lot of talent for him to notice a bright new star in Cassiopeia, though. Tycho logged it 450 years ago tonight. He studied the star extensively, so today it’s known as Tycho’s Supernova. At the time, the heavens were considered not only unchanging, but unchangeable. A new star suddenly flaring to life didn’t fit that m...
Moon and Aldebaran
November 09, 2022 06:00 - 2 minutes - 1.03 MBYou won’t find a much quieter place in the solar system than the far side of the Moon. The Moon doesn’t produce any radio noise, and it blocks radio signals from Earth. That could make it a good site for radio telescopes. But it’ll take a lot of work to build them — and to keep the farside nice and quiet. Radio telescopes are needed to study the Dark Ages — the period in the early universe when the first stars and galaxies were taking shape. The energy from that era is visible mainly at rad...
Uranus at Opposition
November 08, 2022 06:00 - 2 minutes - 1.03 MBThousands of planets have been found in other star systems. They’re all so far away, though, that most are no more than squiggly lines on a computer screen. Yet scientists are slowly teasing the details out of the squiggles. To understand how difficult the problem is, consider that there’s still a lot to learn about the planets of our own solar system. One mystery, for example, is why the planet Uranus radiates very little energy into space. The four outermost planets — Jupiter, Saturn, U...
Eclipse Seasons
November 06, 2022 05:00 - 2 minutes - 1.03 MBIt’s eclipse season! There was a partial solar eclipse a couple of weeks ago. And on Monday night, we’ll have a total lunar eclipse. That one will be visible across all of the United States. It’s not a coincidence that the eclipses are taking place two weeks apart. In fact, eclipses always come in pairs — unless they come in threes — and always two weeks apart. That’s because eclipses require precise alignments of Earth, Sun, and the new or full Moon. But the Moon’s orbit around Earth is t...
Swift Descent
November 05, 2022 05:00 - 2 minutes - 1.03 MBBlack swifts love moonlight — the brighter the better. A recent study found that the birds climbed to their highest altitudes when the Moon was full. But when the moonlight was blocked by an eclipse, they dropped in a hurry. Researchers attached small trackers to a group of black swifts in Colorado. They then tracked the birds during their 4,000-mile migration to the Amazon Basin in Brazil. It took about eight months for the small birds to make the trip — with more than 99 percent of their ...
More Moon and Jupiter
November 04, 2022 05:00 - 2 minutes - 1.03 MBJupiter has a bulging waistline. The planet is almost 6,000 miles thicker through the equator than through the poles — the result of diet and activity. Jupiter is the largest planet in the solar system. It’s 11 times the diameter of Earth, and more massive than all the other planets combined. Jupiter grew so large because it was born far from the Sun. At that distance, it was cold enough for the planet’s growing center to incorporate a lot of ice in addition to rock, so it grew big and hea...
Kochab
November 02, 2022 05:00 - 2 minutes - 1.03 MBThe stars that mark the outer edge of the Little Dipper are known as the Guardians of the Pole. That’s because they’re not far from the Pole Star, Polaris. They circle around it all night, every night — like guards on patrol. But a couple of thousand years ago, one of those stars didn’t just guard the pole — it was the pole. Kochab was closer to the celestial pole than any other bright star beginning in about 1500 BC and continuing for two millennia. The pole star changes because of an eff...
Halloween
October 31, 2022 05:00 - 2 minutes - 1.03 MBIf you need some extra chills to go along with your trick-or-treating or other Halloween fun tonight, just look into the sky. It’s filled with ghosts, witches, and Gorgons — the snaked-headed sisters of mythology who turned anyone who looked at them to stone. The Gorgons are four stars in Perseus, low in the northeast as night falls. The brightest of the four represents Medusa, one of the sisters. The other three arc to its right. The bright one is Algol, from an Arabic phrase that means “t...
Elephant’s Trunk
October 29, 2022 05:00 - 2 minutes - 1.03 MBThe trunk of an elephant extends 20 light-years across the constellation Cepheus, the king. New stars are taking shape inside the trunk — especially in the nostrils. But the supply of gas that gives birth to stars is being worn away, so the starbirth won’t last long. The trunk is part of a giant complex of stars, gas, and dust known as IC 1396. It’s a few thousand light-years away. Even so, it’s so big that it spans about five degrees in our sky — 10 times the width of the Moon. And under d...
Arabic Star Names
October 28, 2022 05:00 - 2 minutes - 1.03 MBAs twilight fades out this evening, many prominent stars fade in. There’s Fomalhaut, the lonely “autumn star,” low in the south-southeast. The stars of the Summer Triangle — Deneb, Vega, and Altair — are pinned high in the sky. And the bright orange stars Aldebaran and Betelgeuse climb skyward later on. The stars are different ages, sizes, and types. But one thing they have in common is their names: all of them were adopted from Arabic. The names were passed down in a couple of ways. Some ...
Fomalhaut
October 27, 2022 05:00 - 2 minutes - 1.03 MBThe neighborhood around a star can be dangerous. Comets, asteroids, and even planets can slam together. That can rip them apart and create massive clouds of dust and rock. And those clouds can be deceiving. Consider Fomalhaut, the brightest star of the southern fish. It’s low in the southeast at nightfall and scoots across the south during the night. It’s the only bright star in that region of the sky, so it’s easy to pick out. Fomalhaut is bigger, brighter, and heavier than the Sun — and ...