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February 2, 2011

A beautiful array of stars decorates the southern sky this evening, including the dazzling constellation Orion.

As you watch Orion, your eye is intercepting a steady stream of "messengers" from its stars: the "packets" of light known as photons, which carry important information about the stars themselves.

You can decode some of their messages on your own. Look at Orion's brightest stars, Betelgeuse and Rigel. Betelgeuse is at the top left of the constellation, with Rigel at the bottom right.

Betelgeuse looks orange, while Rigel is blue. The color reveals their surface temperature. Orange stars are cool, while blue stars are the hottest stars of all.

With the help of special instruments, astronomers can decode many more messages from the stars. The messages tell us what chemical elements the stars contain, how fast they're moving toward or away from us, and whether they have unseen companions, such as planets.

The photons can also reveal a star's size and mass. Combined with its temperature, that can tell us its age -- and its fate. The smallest stars will shine for billions of years, while the largest will last only a fraction as long -- and end their lives with powerful explosions.

In fact, that's the fate of both Betelgeuse and Rigel. They're among the most massive stars in the galaxy, so they're time bombs just waiting to explode. And when they do, we'll get the message loud and clear through torrents of photons -- the messengers of the stars.


Script by Damond Benningfield, Copyright 2010


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