StarDate

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

Episódios

  1. há 1 dia

    Stellar Flotilla

    A thousand spacecraft could head for our closest neighboring planetary system in just a few decades. Don’t book your ticket just yet, though – each craft would weigh about as much as a penny. But working together, they could provide a few sharp pictures of the system, and even look for signs of life. A team of scientists and engineers published the idea earlier this year. The team proposed sending the probes to Proxima Centauri. It’s the closest star outside the solar system – four-and-a-quarter light-years away. And it has two confirmed planets. One of them is about the size and mass of Earth, and it’s in the region that’s most comfortable for life. The probes would be equipped with tough but thin “sails” 13 feet wide. A powerful laser would fire at each probe for eight minutes. The pressure of the light would boost the probes to 20 percent of the speed of light. It would take them 21 years to reach their target. The probes would use lasers to stay in touch with each other, and with Earth. About 300 probes could survive the trip. Their instruments could hunt for evidence of life in the planets’ atmospheres. There’s a lot of work to make it happen – advances in materials, lasers, computers, and even our knowledge of the distance to Proxima Centauri. But the researchers said the current rate of advancement should make such a trip feasible in the decades ahead. Script by Damond Benningfield

  2. há 2 dias

    Turbulent Planet

    The winds on a giant planet more than 200 light-years from Earth are like the Big Bad Wolf: they’ll huff and puff and blow your house down. And if that’s not enough of a problem, the temperature can jump by 500 degrees in just a few hours. The planet orbits the star HD 80606. The star is a lot like the Sun. And it has a distant companion star that’s a near twin. They’re in Ursa Major, the great bear. At dawn, the system stands to the upper right of the Big Dipper, although you need a telescope to see it. The planet is HD 80606 b. It’s about four times the mass of Jupiter, the giant of our own solar system. But it’s about the same size as Jupiter, so it’s much denser. Its orbit is one of the most elongated of any known planet – its distance ranges from just three million miles to 85 million. As the planet approaches the star, it’s like being popped into an oven: The amount of energy it receives when it’s closest to the star is 800 times greater than when it’s farthest. So the planet heats up in a hurry. The approach also stirs up the winds. They blow outward from the point that’s in the middle of the hemisphere that faces the star. They may top out at 11,000 miles per hour – huffin’ and puffin’ all the way around this turbulent planet. Script by Damond Benningfield

  3. há 3 dias

    Moon and Antares

    The Moon huddles close to the heart of the scorpion this evening – the star Antares. It’s among the 15 brightest star systems in the night sky. If our eyes could see all forms of light, Antares would look perhaps 10 times brighter still. That’s because it emits most of its energy in the infrared – wavelengths that are too long for the human eye to perceive. All stars emit radiation across the electromagnetic spectrum – from radio waves to X-rays. That includes the Sun. But the mix of wavelengths depends on the star’s surface temperature, which we see as its color. Stars like the Sun are yellow-white. Their energy peaks at visible wavelengths – the type of energy our eyes have evolved to see. Stars that are hotter than the Sun look white or blue. But their light peaks beyond those colors – mainly in the ultraviolet – wavelengths that are much too short for us to see. Antares, on the other hand, is thousands of degrees cooler than the Sun, so it looks orange. But it emits most of its light in the infrared. And it produces a lot of it. The star is a supergiant – far bigger than the Sun. At visible wavelengths, it shines about 10,000 times brighter than the Sun. Throw in the infrared and all the other wavelengths, and it could be a hundred thousand times the Sun’s total brightness – one of the true stunners in our part of the galaxy. Tomorrow: A planetary Big Bad Wolf. Script by Damond Benningfield

  4. há 4 dias

    More Pegasus

    The first planet ever discovered orbiting a Sun-like star is nothing like anything in our own solar system. But it helped astronomers learn more about the history of the solar system. The planet orbits 51 Pegasi. The star is a little bigger, heavier, and brighter than the Sun. The planet is 51 Pegasi b. It’s about half as heavy as Jupiter, the giant of the solar system. But it’s much closer in – just a few million miles from the star. The planet’s gravity causes the star’s light to “wobble” a bit. Precise measurements of that wobble revealed the planet’s details. Astronomers have since discovered hundreds more planets with the same technique, including many planets that are “hot Jupiters” like 51 Pegasi b. There’s no way for such a massive planet to form so close to its star. So it must have been born much farther out, then migrated to its current location. That realization led to theories that the Sun’s giant planets shifted around when the solar system was young. And that could have nudged the small inner planets, including Earth. It might even have pushed closer planets into the Sun – destroying some of Earth’s planetary siblings. Pegasus is in the east at nightfall. Look for four moderately bright stars that form the Great Square, which is tilted on its side. 51 Pegasi is along the top right side of the tilted square. Under dark skies, it’s barely visible to the eye alone. Script by Damond Benningfield

  5. há 5 dias

    Pegasus

    Pegasus has a bit of an identity crisis. The stars that outline its body – the Great Square – don’t all belong to the flying horse. In fact, the brightest of the four stars officially belongs to Andromeda. The Great Square is in the east at nightfall. Its member stars are all bright enough to see even through moderate light pollution. The square is tilted, so it looks more like a diamond than a square. Its brightest member forms the left point of the diamond – the star Alpheratz. It’s about a hundred light-years from Earth. And it consists of two stars, both of which are a good bit bigger, brighter, and heavier than the Sun. In earlier centuries, Alpheratz was considered a member of both Pegasus and Andromeda – it’s a prominent member of the classical outlines of both constellations. But in the early 20th century, astronomers decided to formalize the constellations. In 1930, they adopted a list of 88 constellations and gave them precise boundaries, like the borders of states or nations. That meant that every star could belong to only one constellation. The way the borders were drawn, Alpheratz stayed with Andromeda. There’s no way to not see the star as part of the Great Square. So unofficially, Alpheratz maintains its dual citizenship: the second-brightest star of Andromeda, and the brightest star of the Great Square of Pegasus. We’ll have more about the flying horse tomorrow. Script by Damond Benningfield

  6. há 6 dias

    Moon and Venus

    The United States and China both plan to land astronauts on the Moon in the next few years. And scientists from both countries are working on the best landing sites – places that are safe and easy to operate from, but that offer some interesting science. One of China’s possible sites is just north of the equator, near the center of the hemisphere that faces Earth. It offers a range of geologic features, spanning almost all of lunar history. The site is known as Rimae Bode. It’s along the boundary between a smooth volcanic plain – the Sea of Vapors – and a more jumbled region in the lunar highlands. It features ancient lava flows, deep channels, layers of volcanic ash, and material blasted out of a nearby crater. Samples from these regions would help scientists piece together more than four billion years of impacts, volcanic activity, and other events. Planetary scientists are especially interested in the layers of ash, which also contain tiny glass beads. The material might have been blasted from deep below the surface billions of years ago. They would provide details about the Moon’s interior – hard-to-come-by insights into our satellite world. The crescent Moon teams up with the planet Venus in the early evening sky the next couple of nights. Venus is the brilliant “evening star.” But they’re quite low as twilight fades, so there’s not a lot of time to enjoy the view before they set. Script by Damond Benningfield

  7. 12 de set.

    Capricornus

    The roster of constellations includes some weird and wonderful creatures. There’s a dragon, a unicorn, and two centaurs. But perhaps the weirdest of all is Capricornus, the sea-goat – it’s half goat and half fish. It’s associated with the god Pan, who was half goat and half man. The story says that he was about to be attacked by the monster Typhon, so he jumped into the water to escape. At the same time, he tried to transform himself into a fish to speed his getaway. But he botched the spell, and turned his human half into a fish, but kept the half that was a goat. The constellation is low in the southeast as darkness falls at this time of year. Its brightest stars form a wide triangle. None of the sea-goat’s stars is all that bright, though, so you need a fairly dark sky to make them out. The brightest forms the left point of the triangle. It’s known as Deneb Algedi – “the tail of the goat.” It’s actually a system of at least two stars. One is about twice as big and heavy as the Sun, and shines several times brighter. The other is a lot like the Sun. The stars orbit each other about once a day. As they do, each one passes in front of the other for a bit. When the fainter star crosses the brighter one, the system’s overall brightness drops by about a quarter. That’s just enough for a skilled observer to notice with the eye alone – a slight flicker in one of the night sky’s oddest creatures. Script by Damond Benningfield

  8. 11 de set.

    Demolished Planets

    Young star systems are dangerous places. A planet can be pelted by giant asteroids and comets. It can collide with its siblings, and be kicked out of the system by close encounters with other siblings. It might even be swallowed by its parent star. Astronomers in the U.K. recently found evidence of such encounters in several young stars. The researchers zeroed in on stars in three clusters. All of the clusters are young – from about 40 million to 200 million years old. At that age, their star systems might still be chaotic – planets might be getting blasted or destroyed, and they might still be taking shape. Six stars in the clusters showed especially high amounts of lithium. It’s a common planet-building material. But it’s fragile – stars quickly destroy it. So any lithium in the stars must have been added recently. The most likely source is young, rocky planets. The planets could have been kicked inward by the gravity of other planets, or dragged in by gas and dust around the stars. Over time, the remains churn deep into a star’s interior. But some can linger for a few million years – the remains of dead planets. One of the clusters is Blanco 1. It’s 850 light-years away, in the constellation Sculptor. It climbs into the southeast in mid evening, to the lower left of the bright star Fomalhaut. It’s too faint to see with the eye alone, but it’s a decent target for small telescopes. Script by Damond Benningfield

  9. 10 de set.

    Lemon Planet

    A planet orbiting a dead star 750 light-years from Earth is a real lemon. The planet is shaped like a lemon – a result of the extreme gravity of its parent star. The system is PSR J2322-2650. The star is a pulsar – the crushed corpse of a once mighty star. It’s heavier than the Sun, but only about as wide as a small city. It spins almost 300 times per second, beaming out “jets” of energy. One of the jets sweeps across Earth, so the star appears to “pulse” on and off. The pulsar is so dense that its surface gravity is about a hundred billion times stronger than Earth’s gravity. And the planet is only about a million miles away – about one percent the distance from Earth to the Sun. At that range, the pulsar’s gravity stretches the planet – making it look like a lemon. The planet is about as massive as Jupiter, the giant of our own solar system. And it has a thick atmosphere made mainly of carbon and helium – a combination that scientists can’t explain. Gamma rays from the pulsar heat the planet’s dayside to 3700 degrees Fahrenheit. So you’d need a lot of lemonade to stay cool on this lemon planet. The system is too faint to see with the eye alone, but it’s easy to pick out its location. It’s low in the southeast by mid-evening, close to the left of Fomalhaut – the only bright star in that region of the sky. We’ll talk about another sight close to Fomalhaut tomorrow. Script by Damond Benningfield

  10. 9 de set.

    More ‘G’ Stars

    The Sun belongs to a rare class of stars: Class G. Members of this class account for only seven or eight percent of all the stars in the Milky Way Galaxy. A star’s class is determined by its surface temperature, which we see as its color. G stars are in the middle of the temperature scale, so they shine yellow or yellow-white. Most class-G stars are in the prime of life – a span that puts them on the main sequence. They’re steadily “fusing” the hydrogen in their cores to make helium. And most of them will stay in that phase of life for 10 billion years or longer. Most of them are within about 15 percent of the mass of the Sun. Any heavier and they’d get hot enough to move up to class F or higher. Any lighter and they’d be cool enough to move down to class K or M. Main-sequence G stars are only a small fraction of the size, mass, and brightness of the top stars. But the stars in higher classes are even more rare than G stars. So the Sun, which is near the top of its class, shines brighter than about 90 percent of the stars in the Milky Way. Not all G stars are on the main sequence, though. Some are bloated and heavy. Such stars are more massive than the Sun. They’ve burned through the hydrogen in their cores, and are fusing hydrogen in a thin shell around the core. But they’re undergoing a transition, so they won’t stay yellow for long – the short-lived monsters of class G. Script by Damond Benningfield

  • 10 episódios

Apresentadores e convidados

Sobre

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

Informações

  • Criado por
    Billy Henry
  • Anos de atividade
    2017 - 2026
  • Episódios
    10
  • Classificação
    Livre
  • Copyright
    © 2022 The University of Texas McDonald Observatory
  • Site do podcast
    StarDate

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