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Seeing Double

May 30, 2010

Two pairs of "twins" decorate the western evening sky the next couple of weeks. One pair always teams up, while the other is just temporary -- the twins will soon go their separate ways.

As darkness falls, look about a third of the way up the western sky for Pollux and Castor, the stars that represent the twins of Gemini. They're especially easy to spot right now because they're above Venus, the "evening star."

Pollux is the brighter of the two, and shows a distinctly orange color. Castor is to its right, and shines pure white. They'll drop lower in the sky each night throughout June, and by month's end, they'll be just about lost in the twilight. They'll return to view by midsummer -- but this time in the morning sky.

The other pair of "twins" is well to the upper left of Gemini at nightfall, and looks like a mirror image of Pollux and Castor. It's the star Regulus, which marks the heart of Leo, the lion, and the planet Mars. Mars is almost the same brightness as Pollux, and glows with the same orange color. Regulus, to the left of Mars, is a bit fainter than the planet. And although it's brighter than Castor, it also looks white.

But the pairing of Mars and Regulus is only temporary. Over the next week or so, Mars will move closer to the bright star, then pass it by. It'll then race away from Regulus, and by the end of June, a good gap will have opened between them -- and Mars and Regulus will look like "twins" no more.

Script by Damond Benningfield, Copyright 2010

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