StarDate

Billy Henry
  • 4.6 (262)
  • Astronomy
  • Updated Semiweekly

StarDate, the longest-running national radio science feature in the U.S., tells listeners what to look for in the night sky.

Episodes

  1. 1d ago

    More Venus and Jupiter

    If you look toward the west the next couple of evenings and feel like you’re having double vision – well, you are. But it’s nothing to worry about. It’s a conjunction between the two brightest points of light in the night sky – the planets Venus and Jupiter. They’re separated by less than two degrees – the width of your finger held at arm’s length. Venus is the brighter point – the brilliant “evening star.” Jupiter is only about one-seventh as bright, but it still outshines all the other planets and stars. Jupiter is the largest and heaviest planet in the solar system. It’s a ball of gas with a dense, oozy center. Its atmosphere is topped by bands of clouds painted tan, yellow, red, and ivory. The clouds reflect most of the sunlight that strikes them, making the planet bright. Venus is only the sixth-largest and -heaviest planet – right behind Earth. It’s also covered by clouds. But they don’t form colorful stripes. To the eye alone, in fact, they look featureless – a smooth blanket of white. But they’re more reflective than Jupiter’s clouds. Venus is also much closer to both Earth and the Sun than Jupiter is. That combination makes it the brightest pinpoint in the night sky. Venus and Jupiter will be closest together tonight and tomorrow night. Then Venus will pull away, increasing the gap by about one degree per night – slowly ending the “double vision” in the evening sky. Script by Damond Benningfield

    2 min

  2. 2d ago

    Death-Ray Galaxy

    Any residents of a galaxy in the constellation Serpens have a big problem: They’re being blasted by a death ray from a black hole. The galaxy is a companion to a bigger galaxy, known as 3C321. They’re more than a billion light-years away. A supermassive black hole inhabits the heart of the larger galaxy. It’s surrounded by a giant disk of gas that’s heated to millions of degrees. Powerful magnetic fields funnel charged particles from the disk into jets. They squirt away from the poles of the black hole at almost the speed of light. One of those jets is firing toward the companion galaxy, which is just 20,000 light-years away. Observations by telescopes on the ground and in space show that the jet is hitting the edge of the companion, creating a hotspot. The encounter deflects the beam off its original course, but the beam continues for hundreds of thousands of light-years. The particles and radiation in the beam could destroy the ozone layer of any planet the beam hits. That would leave the planet exposed to radiation from the beam itself, and from other cosmic sources. So anything living on the planet would be in danger. And the situation is getting even worse. The smaller galaxy appears to be just entering the black-hole jet. Over time, more of the galaxy will pass through the jet – possibly exposing even more planets to this “death ray” from another galaxy. Script by Damond Benningfield

    2 min

  3. 3d ago

    The Serpent

    The sky is divided into 88 official constellations. In fact, though, it’s more like 88 and a half. That’s because the constellation Serpens consists of two disconnected parts – a head and a tail. They wrap “behind” the body of Ophiuchus the serpent bearer. Serpens is in full view in the east and southeast by a couple of hours after sunset. The half that represents the head is highest, above Ophiuchus, with the tail below the serpent bearer. The front of the snake, Serpens Caput, is the more prominent half. It has several stars that are fairly easy to see. The brightest is Alpha Serpentis, also known as Unukalhai – “the serpent’s neck.” It’s a red giant – an old, bloated star that’s much bigger and brighter than the Sun. Its surface is much cooler than the Sun’s, so the star looks yellow-orange. The back half of the snake, Serpens Cauda, is tougher to spot. Its brightest star, Eta Serpentis, is the second-brightest star in the whole constellation. It’s about half as bright as Alpha. But the two stars are quite similar. Eta is also a giant – a puffed-up star that’s nearing the end of its life. It’s a little farther along than Alpha, so it’s a little bigger and brighter. It looks fainter because it’s farther away. The two stars will end their lives in the same way. Each will cast its outer layers into space, leaving behind a hot but tiny corpse known as a white dwarf. More about Serpens tomorrow. Script by Damond Benningfield

    2 min

  4. 4d ago

    Venus and Jupiter

    Venus and Jupiter are staging one of the top skywatching events of the year – an especially close encounter of the two brightest points of light in the night sky. It plays out in the west over the next few evenings. Venus is the beautiful “evening star” – the brightest object in the night sky after the Moon. Jupiter is the next-brightest. Even so, right now it’s only about one-seventh as bright as Venus, so it’s easy to tell them apart. The two planets can pass especially close because both of them stay near the ecliptic – the Sun’s path across the sky. They pass by each other every year or so. But both worlds wander a little bit to either side of the ecliptic, so they usually just miss each other. And even when they are close, they’re sometimes so near the Sun that we can’t see them. At times, though, Venus can pass in front of Jupiter, blocking it from view That last happened in 1818. It’ll happen again in 2065. But that’s one of those times when they’ll be too close to the Sun to see. Tonight, Jupiter is close to the upper left of Venus. But over the coming evenings, Venus will overtake it. They’ll stand side by side on Sunday, and be especially close on Monday and Tuesday – separated by about the width of your finger held at arm’s length. They don’t drop from view until about 10:30 or 11, so there’s plenty of time to watch this impressive planetary encounter. Script by Damond Benningfield

    2 min

  5. 5d ago

    Tie-Dyed Sky

    The night sky can sometimes look like a tie-dyed T-shirt flapping on a clothesline. Ribbons and swirls of bright color ripple through the sky. They can change appearance in seconds – blown by the solar wind. The colorful display is an aurora – the northern and southern lights. An aurora flares to life as charged particles from the Sun run into Earth at high speed. Earth’s magnetic field funnels the particles toward the magnetic poles. When particles hit atoms and molecules high above the surface, they knock atoms out of their usual configuration. When they return to normal, the atoms emit light. The color of an aurora depends on what the charged particles hit, and where they hit it. Most auroras are green. They switch on when particles hit oxygen molecules at altitudes of about 60 to 200 miles. Red auroras are fed by oxygen that’s even higher. The lower fringes of a display can appear pink or dark red – the result of collisions with nitrogen at lower altitudes. Collisions with hydrogen and oxygen create blue and purple auroras. But they’re not very common, and they’re hard for the eye to take in. They’re easier to see in photographs. Most of the time, the northern lights stay close to the magnetic pole. When the Sun spews out more particles, though, they can spread outward, shining in regions where they’re seldom seen. And the colors can get more intense – dramatically “tie-dying” the night sky. Script by Damond Benningfield

    2 min

  6. 6d ago

    Glaring Visage

    The goddess of the dawn has given millions of Americans a rare treat the past couple of years: brilliant displays of the northern lights in regions where they’re seldom seen. Today, we know that these colorful curtains of light are powered by storms on the Sun. Bigger storms expand the viewing area. But in centuries past, cultures around the globe created their own explanations. In Scandinavia, for example, the northern lights might have represented Bifrost, the “rainbow bridge” that connected Earth to Asgard, the home of the gods. In some of the islands of Scotland, the lights represented a pair of chieftains fighting for the hand of a “merry dancer.” In southern England, they were considered omens of misfortune. Some saw the lights as clashing swords; red lights were streamers of blood. During an intense outburst in March 1716, at the end of a civil war, people ran into the streets in their nightclothes, and some thought it was judgment day. One writer said that some “read in its glaring visage, the fate of nations and the fall of kingdoms.” The name for the northern lights – the aurora borealis – was bestowed in 1619 by Italian astronomer Galileo Galilei. Aurora was the Roman goddess of the dawn. Boreas was the Greek god of storms and the north wind – one of the namesakes of the always beautiful, sometimes frightening northern lights. More about the aurora tomorrow. Script by Damond Benningfield

    2 min

  7. Jun 2

    Surveyor 1

    Sixty years ago today, NASA was making its first attempt to land on the Moon. Surveyor 1 had been launched three days earlier. The robotic lander touched down in a crater in the Ocean of Storms – a giant volcanic plain. It was a precursor to the Apollo missions, which would land astronauts on the Moon. Surveyor wasn’t the first probe to land on the Moon – a Soviet mission beat it by a few months. But Surveyor was more sophisticated. It carried a television camera to beam back images of its surroundings. Surveyor transmitted its first pictures just minutes after landing. And during its first lunar “day” – almost 14 Earth days – it snapped more than 10 thousand images. They showed a surface coated with small rocks, and pockmarked by small craters. The rim of the crater Surveyor landed in was visible in the distance. Pictures of its landing pads revealed important details about the texture of the lunar surface, as this NASA documentary pointed out:  ANNOUNCER: The lunar surface texture not thick layers of loose dust into which spacecraft or men could sink. In the area of the Ocean of Storms, man can land and walk on the lunar surface. Surveyor 1 survived the frigid lunar night, taking hundreds more pictures the next day. Scientists even raised it the following January – seven months after its historic landing on the Moon. Script by Damond Benningfield

    2 min

  8. Jun 1

    Evening Planets

    The twins of Gemini have a front-row seat for a planetary waltz this month. Venus, Jupiter, and Mercury are close to the twins now, and will bunch up even closer as the month progresses. The “twins” are the stars Pollux and Castor. They’re about a quarter of the way up the western sky as evening twilight fades. Pollux is the brighter of the two, with Castor to its right. Jupiter looks like a brilliant star to the lower left of the twins. It’s the largest planet in the solar system. But it’s on the far side of the Sun as seen from Earth, so it’s more than 550 million miles away – about six times the distance between Earth and the Sun. Venus is even brighter – the “evening star.” It’s below the twins. Although it’s a little smaller than Earth, it shines much brighter than Jupiter mainly because it’s much closer to both Earth and the Sun. Venus and Jupiter remain in view for a good while after darkness falls. That’s not the case for Mercury. It’s well to the lower right of the others, and much lower in the sky. It’s bright, though, so with a clear horizon, there’s a good chance to spot it. Mercury will move a little higher into the sky over the next few nights, improving the view. But the real action involves Jupiter and Venus. Venus is climbing away from the Sun quickly. It will nestle especially close to Jupiter on the 8th and 9th. It’ll pull away after that – all in close view of the twins. Script by Damond Benningfield

    2 min

  9. May 31

    Cold Skies

    It’s early in the long winter night at the south pole. But a few dozen scientists and others have settled in at a research base there. They monitor the weather and climate, listen to rumbles in the ice below, and watch auroras dancing in the dark skies above. And they operate observatories that study the universe beyond. One of those observatories is buried in the ice. Known as IceCube, it’s a set of thousands of light detectors. They look for evidence of neutrinos – particles that are produced in the Sun, exploding stars, and other powerful objects and events. They almost never interact with other matter. But when one does interact, by smashing into an ice molecule, it produces a quick flash of light. Studying that flicker reveals details about the neutrino, including its origin. And that tells scientists more about the body that created it. Another observatory, the South Pole Telescope, studies the “afterglow” of the Big Bang. Known as the cosmic microwave background, it’s a sort of “haze” that fills the entire universe. Tiny fluctuations in the haze reveal details about the birth of the first stars and galaxies. Water vapor in the atmosphere absorbs microwaves. But the south pole is almost two miles high, and it’s so cold that there’s almost no water vapor in the skies above it. That allows the 10-meter dish to study the background glow in great detail – under the clear, dark skies at the bottom of the world. Script by Damond Benningfield

    2 min

  10. May 30

    Blue Moon

    The Moon can be like a painter’s canvas, dabbed with many colors: the silver of a frosty night, the gold of honey, the orange of a ripe cantaloupe, even the deep red of blood. But it’s almost never blue – at least not in appearance. It sometimes is blue in name, though – including tonight. That’s because it’s the second full Moon of May – a repeat appearance known as a Blue Moon. The color of the Moon – full or not – depends on several factors. When the Moon is low in the sky, as it rises or sets, its light passes through a thicker layer of air. Molecules in the atmosphere scatter blue wavelengths of light, allowing the red to shine through. As the Moon climbs higher, we see more of its true color – gray. But the Moon is so bright that it looks white or silver. During a lunar eclipse, the Moon passes through Earth’s dark shadow. But sunlight filtering through Earth’s atmosphere makes the Moon look dark orange or red. In rare cases, the Moon can actually look blue. That happens after volcanic eruptions or big forest fires. These events pump out particles that scatter red light, allowing the blue to shine through. After the eruption of Krakatoa, in 1883, the Moon appeared blue for months around the entire globe. Whatever its color, enjoy tonight’s Blue Moon. And look quite close to it throughout the night for the star Antares, the heart of the scorpion. They’ll be closest as they set. Script by Damond Benningfield

    2 min
  • 10 Episodes

Hosts & Guests

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About

StarDate, the longest-running national radio science feature in the U.S., tells listeners what to look for in the night sky.

Information

  • Creator
    Billy Henry
  • Years Active
    2017 - 2026
  • Episodes
    10
  • Rating
    Clean
  • Copyright
    © 2022 The University of Texas McDonald Observatory
  • Show Website
    StarDate

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