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Venus and Aldebaran

April 8, 2012

Taurus, the bull, eyes the planet Venus the next few nights, as they line up close together in the western evening sky. Venus is the brilliant “evening star.” Taurus’s orange “eye,” the star Aldebaran, is to the left of Venus. They’re well up in the sky at nightfall, and set before midnight.

Although Venus and Aldebaran are quite different objects, their futures have something in common.

Aldebaran is a type of star known as a red giant. It’s nearing the end of its life, so it’s puffed up to gigantic proportions, which is why it shines so brightly.

Over millions of years, though, Aldebaran will shed its outer layers. Only its hot but tiny core will remain -- a white dwarf.

That process of puffing up, then sloughing off its outer layers, will destroy any planets that are close to Aldebaran. And that’s what Aldebaran and Venus have in common.

Several billion years from now, the Sun will become a red giant, puffing up to perhaps hundreds of times its current size. As it does, it’ll produce thicker “winds” of hot gas than it does today. Since Venus is the second planet out from the Sun, friction from the winds will slow it down and pull it closer to the Sun. As the Sun reaches giant proportions, it’ll engulf Venus -- and perhaps Earth, too.

So Venus will end its life in the embrace of a red giant -- a star that’ll look a lot like Aldebaran does today.

We’ll have more about the next step beyond a red giant -- a white dwarf -- tomorrow.


Script by Damond Benningfield, Copyright 2012


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