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Moon and Antares

May 17, 2011

The lives of the stars don't always make much sense, whether they're stars here on Earth or far out in space.

In the realm of the astronomical stars, for example, you might expect the biggest and heaviest stars to live the longest lives. But the truth is just the opposite. The bigger and heavier a star gets, the shorter its lifetime.

Compare our own star, the Sun, with giant Antares, the bright orange "heart" of Scorpius, the scorpion. Antares rises just below the Moon a couple of hours after sunset tonight, and remains close to the Moon all night.

Antares is probably at least 15 times as massive as the Sun. As a result of that great heft, its core is much hotter than the core of the Sun, so Antares "burns" through its hydrogen fuel much more quickly. That makes Antares tens of thousands of times brighter than the Sun.

But it also means Antares will live a much shorter life -- tens of millions of years, versus about 10 billion years for the Sun.

And when the Sun dies, it'll gently push its outer layers into space, leaving behind only its hot core -- a white dwarf. It'll be more than half as massive as the Sun is today, but only about as big as Earth.

Antares, on the other hand, will blast itself apart in a titanic explosion known as a supernova. It will leave behind a corpse, too: most likely a neutron star -- a ball several times the mass of the Sun, but no bigger around than a city -- a tiny corpse of a once-mighty star.


Script by Damond Benningfield, Copyright 2011


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