The Bull's Eye

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The baleful eye of Taurus, the bull, stares unblinking from high in the sky tonight -- the orange star Aldebaran. It's one of the brightest stars in the night, and one that gives us a glimpse at the fate of our own star, the Sun.

Aldebaran is classified as a giant. The star is much larger than the Sun, and its surface is much cooler -- that's why it looks orange.

In astronomical jargon, though, a "giant" star isn't just a big one -- it's one that's entering the final stages of life. It's used up the original hydrogen fuel in its core, and is burning through the helium "ash" created in its nuclear fires. The core shrinks and heats up as this happens, while the other layers expand to giant proportions.

Aldebaran, for example, is about 40 times wider than the Sun. If it took the Sun's place, it would stretch halfway out to the orbit of Mercury, the solar system's innermost planet. Its energy would boil away Earth's oceans, turning our planet into a burned-out cinder.

The Sun is probably close to halfway through its "normal" lifetime, which means that it won't become a giant for several billion years. When it does, it'll shine far brighter than it does now -- briefly decorating the night skies of worlds that are hundreds of light-years away.

Look for Aldebaran high in the southeast this evening. It's at one point of a V-shaped pattern of stars. The V outlines the bull's face -- with Aldebaran as his giant orange eye.

Script by Damond Benningfield, Copyright 2008

For more skywatching tips, astronomy news, and much more, read StarDate magazine.