Vegan Planets?

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In "Contact," a novel by Carl Sagan, an astronomer discovers a radio signal beamed into space from the star Vega. Real-life astronomers haven't found such a signal -- from Vega or any other star. But they have discovered either planets or the material for planets orbiting more than 250 stars. And in the case of Vega, they may have found both.

More than two decades ago, they discovered that a wide disk of dust grains surrounds Vega. But the disk has big lumps and gaps. These may be caused by the gravity of planets that orbit the star, which sweep away the dust in some areas of the cloud, and cause it to clump together in others.

The clumps may be caused by a planet about as massive as Neptune, one of the giants of our own solar system. But there's evidence of smaller planets, too.

None of these planets, if they exist, is a likely home for life. Vega's only about 350 million years old -- less than one-tenth the age of the Sun -- so there probably hasn't been enough time for life to evolve there. And even if life did form, Vega's much hotter than the Sun, which makes it an unfriendly environment.

Vega is the brightest member of the Summer Triangle, which is in view all night. Vega's well up in the east-northeast at nightfall, and climbs high overhead during the wee hours of the morning. It's a star well worth keeping an eye on -- even if there's no one there to contact.

More about the Summer Triangle tomorrow.

Script by Damond Benningfield, Copyright 2004, 2008

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