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Venus and Gemini

June 10, 2010

The planet Venus lines up with the twins of Gemini in the western sky the next few evenings -- the stars Pollux and Castor. Venus is the brilliant "evening star." Pollux is to the right of Venus, with Castor about the same distance to the right of Pollux.

Pollux appears to have at least one planet of its own -- and it's a big one. It's three times as massive as Jupiter, the giant of our own solar system. It's much closer in than Jupiter is, though. So unlike Jupiter, whose cloudtops are quite cold, this planet should be red hot.

And that's not just because the planet is closer to its parent star, though. It's also because Pollux is a giant -- it's much larger than the Sun is, and it emits much more energy into space. So each square mile of the planet receives far more energy from Pollux than Earth receives from the Sun.

Like Jupiter, the planet's probably a big ball of gas. So with all of that heat from Pollux, the top of its atmosphere is probably churning like crazy.

But the worst is yet to come. Pollux is a stellar giant. It's nearing the end of its life, so its outer layers have puffed up like a balloon. But that's only the first stage of the star's "gianthood." Later on, it will puff outward even more -- filling most of the space out toward the planet. It'll boil away the planet's layers of gas, leaving nothing more than a burned out cinder -- a bit of cosmic ash orbiting a dead star.

More about Venus and Gemini tomorrow.

Script by Damond Benningfield, Copyright 2010

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