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Moon and Antares

April 20, 2011

An astronomical supergiant leads the Moon across the sky in the wee hours of tomorrow morning: Antares, the bright orange star to the Moon's right or lower right.

Antares is one of the biggest stars in the galaxy -- about 600 million miles in diameter -- six times the distance from Earth to the Sun.

Such a big, bright, heavy star isn't a likely home for life-bearing planets.

For one thing, a planet would have to be tens of billions of miles from Antares for the temperature to be right for liquid water -- a necessary ingredient for life like that on Earth. So far, no one's discovered a planet that far from any star, and planetary scientists aren't even sure if planets can be born that far out. And Antares has a companion star that might have interfered with the birth of planets.

Even more important, though, is the age of such a star. Antares is only a few percent of the age of the Sun, so there probably hasn't been enough time for life to form there. And time is quickly running out. Sometime in the next million years or so, Antares is likely to blast itself apart as a supernova. So even if a planet survived the explosion, it would be zapped by deadly radiation, and deprived of its source of light and heat: the supergiant star Antares.

Again, look for Antares close to the Moon tonight. They rise in late evening, and are in good view at first light.

Script by Damond Benningfield, Copyright 2011


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