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February 8, 2010

The most beautiful of all the "connect-the-dots" constellations is in grand view on winter evenings. Orion, the hunter, is in the southeast at nightfall, and wheels high across the south later on.

Orion's most prominent feature is his belt -- a line of three fairly bright stars near the middle of the constellation. From left to right, they're Alnitak, Alnilam, and Mintaka. The three stars aren't related -- they just happen to line up in the same direction in the sky. But they're similar types of stars -- far bigger, hotter, and brighter than the Sun.

So are Orion's two brightest stars -- orange Betelgeuse to the upper left of the belt, and blue-white Rigel to the lower right. Both are classified as supergiants, which means they're some of the biggest and most powerful stars in the galaxy. And both are slated to end their lives in spectacular fashion: They'll blast themselves to bits as supernovae.

While these stars near the ends of their lives, another feature in Orion is giving birth to new stars: the Orion Nebula. It's below the belt, and looks like a small, faint smudge of light. It's really a vast complex of gas and dust. Pockets of this material have collapsed to give birth to thousands of stars, with many more still taking shape. The most massive of these stellar infants, near the center of the nebula, will also die as supernovae -- making Orion look even more spectacular.

We'll have more about the Orion Nebula tomorrow.

Script by Damond Benningfield, Copyright 2009

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