Venus and Antares

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By everyday standards, our Sun is a giant. It's the largest object in the solar system, with a diameter more than a hundred times that of Earth. And even by the standards of the stars it's a good size -- bigger than perhaps 90 percent of the stars in the galaxy.

Even so, a few stars make it look positively tiny by comparison. A prime example is Antares, the "heart" of Scorpius, the scorpion. The bright orange star is quite low in the southwest as twilight fades this evening. It's a little below the planet Venus, the brilliant "evening star."

Antares is classified as a supergiant. It's several times as massive as the Sun, but much bigger. In fact, Antares is so big that if it took the Sun's place, it would swallow the four inner planets -- including Earth -- and come darn close to the orbit of Jupiter.

But diameter is only one measure of the star's size. Even more impressive is its volume. It's big enough to hold several hundred million Suns. To look at it another way, Antares is big enough to encompass every member of the smallest class of stars in the galaxy, known as red dwarfs. Or to turn it into everyday terms, if the Sun were the equivalent of an Olympic swimming pool, Antares would be Lake Michigan.

But this giant star won't last for long. Within a million years or so, Antares will blast itself apart as a supernova -- while the Sun and all those little stars shine on.

Tomorrow: swimming with the stars.

Script by Damond Benningfield, Copyright 2008

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