StarDate PodcastAuthor: McDonald Observatory
20 Sep 2020

StarDate Podcast

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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.

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    Vulpecula

    A fox carries a goose high across the sky this evening. You need dark skies to pick them out, and a vivid imagination to “see” them.

    The constellation Vulpecula stands high in the southeast at nightfall. It’s near the middle of the Summer Triangle, which is defined by the stars Vega, Deneb, and Altair.

    Johannes Hevelius created the constellation more than three centuries ago. His original name for it was Vulpecula cum Anser — fox with goose. He showed it as a fox holding a goose in its jaws.

    Perhaps the fox later ate the goose, or perhaps the goose escaped and flew away. Whatever the reason, the name was shortened to just Vulpecula — the fox. The goose is still remembered, though, in the name of the constellation’s brightest star — Anser. It’s not much to look at. In fact, you need dark skies to see the star at all.

    The star itself is actually pretty impressive. It’s a red giant — a dying star that’s puffed up like a giant balloon. But its distance of 300 light-years dulls its luster.

    One of Vulpecula’s claims to fame is the first pulsar. When it was discovered more than a half-century ago, there was a brief hope that it might be a signal from another civilization. But follow-up work showed that it was the crushed, rapidly spinning core of a dead star — an impressive discovery in its own right.

    Another dying star has created another impressive object in Vulpecula: the Dumbbell Nebula. We’ll have more about that tomorrow.


    Script by Damond Benningfield

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  • Posted on 19 Sep 2020

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    Dark Planet

    The planet known as TrES-2b sounds like it should glow like wild. It’s only about three million miles from its parent star — much closer than Mercury is to the Sun. And its night side may sizzle at almost 3,000 degrees. Yet the planet appears to be the darkest yet seen — darker than charcoal.

    TrES-2b is named for the project that discovered it — the Trans-Atlantic Exoplanet Survey. The planet orbits a star that’s a near twin to the Sun — it’s the same size, mass, and temperature. It’s about 750 light-years away.

    TrES-2b is a giant ball of gas. It’s bigger and heavier than Jupiter, the giant of our own solar system. And it’s “locked” so that the same hemisphere of the planet always faces the star, just as the same side of the Moon always faces Earth. Powerful winds may carry some of the daytime heat to the nightside.

    TrES-2b appears to reflect no more than one percent of the light from its star. By comparison, the Moon, which is quite dark, reflects about 10 percent of the sunlight that hits it.

    The planet may be so dark because the heat prevents bright clouds from forming in its atmosphere. Or dark, heavy compounds in the atmosphere may absorb light — leaving TrES-2b in the dark.

    The TrES-2 system is high overhead at nightfall, at the edge of Draco, the dragon. The star is too faint to see without a telescope. But it’s near one of the wingtips of Cygnus, the swan, which soars high across the sky in early evening.


    Script by Damond Benningfield

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  • Posted on 18 Sep 2020

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    Rapid Birth

    When it comes to making planets, star systems may not waste much time. A recent study says that planets may form in less than a million years — the blink of an eye in the lifetime of a star.

    Planets form when bits of debris around a newborn star stick together. Chunks of ice and rock can merge to form bodies the size of Earth or bigger. Bodies that are far away from the star can then sweep up huge amounts of leftover gas and dust. That makes giant planets, such as Jupiter and Saturn in our own solar system.

    Observations of star systems that are as young as one million years, though, have shown a dearth of the dust grains needed to make Jupiter-sized planets. That could mean that such systems won’t give birth to giant planets — or that they already have.

    In a recent study, astronomers used arrays of radio telescopes in New Mexico and Chile to study especially young star systems in Perseus. The systems are no more than a half-million years old — mere infants. The astronomers found that the systems contain plenty of dust for making planets. That suggests that giant planets can form in a million years or less — the blink of an eye.

    Perseus is climbing into the evening sky this month. Tonight, it’s in good view, in the northeast, by about 10:30. It rises a few minutes earlier each night, providing plenty of time to enjoy one of the highlights of the autumn sky.

    Tomorrow: a “hot coal” of an exoplanet.


    Script by Damond Benningfield

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  • Posted on 17 Sep 2020

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    Hunting ET

    ET is quiet. Searches for radio signals from other worlds have come up empty. And while the search continues, astronomers are thinking up ways to broaden the hunt. They’re looking for “signatures” of intelligent life other than radio transmissions. And they’re pondering just how many civilizations that are as “talkative” as our own might be out there.

    One new study, for example, will hunt for two kinds of “technosignatures.” One of them is industrial pollution in a planet’s atmosphere. Molecules like CFCs — compounds that’ve damaged Earth’s ozone layer — don’t occur naturally. So if they show up in a planet’s atmosphere, they must have been put there by a civilization.

    The other signature is the “glow” of massive arrays of solar cells on a planet’s surface or in the space around it. Researchers will identify which wavelengths they need to scan to see that glow.

    Another study found that talkative civilizations probably are pretty rare. The study considered some features of stars that are key to life. And it assumed that other civilizations would develop in about the same length of time as our own.

    The study said there should be about three dozen civilizations in the galaxy that are at the same stage of development as our own. They would be emitting radio waves, just as we do. But they’d be so far away that current technology might not be able to hear them. So we’d need new ways to discover these distant civilizations.


    Script by Damond Benningfield

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  • Posted on 16 Sep 2020

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    More Trappist-1

    If anyone lives on the planet known as Trappist-1e, they should know their neighbors pretty well. There are six other confirmed planets in the system, and they’re all packed close together. As a result, they all pass within a few million miles of planet e. And two of them pass within about half a million miles — about twice as far as the Moon is from Earth. Since the planets are all bigger than the Moon, they’d be big presences in the sky.

    The big question is whether anyone is there to enjoy the view. Scans for radio signals produced by a civilization there have come up empty. And our telescopes can’t see the planet clearly enough to know just what conditions are like. Even so, Trappist-1e is considered one of the best candidate worlds for life.

    The planet is in the system’s “habitable zone.” That’s the distance from the star where conditions are most comfortable for life. And the planet is a lot like Earth. It could have a fairly thick atmosphere, and perhaps even big oceans.

    Life would face some challenges, though. While the planet’s parent star is quite feeble, for example, it sometimes produces big outbursts of radiation that could damage the planet’s atmosphere.

    But there’s plenty of time for life to take hold on Trappist-1e. The system is already a few billion years older than the Sun. And because the star is feeble, it will shine for trillions of years more — lighting up the busy skies of Trappist-1e.


    Script by Damond Benningfield

    Support McDonald Observatory


  • Posted on 15 Sep 2020

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