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Early Summer

December 14, 2010

The start of winter is just a week away, but summer is already making its presence known in the night sky -- at the feet of the celestial twins.

The constellation Gemini is in good view in the eastern sky by around 8 o'clock. It's best known for Castor and Pollux, the two bright stars that represent the heads of the twins. They're low in the east-northeast at that hour, with Castor above Pollux.

The rest of the constellation stretches to the right -- basically two long streamers of stars. The streamer to the right of Castor ends with a line of three fainter stars that curls upward a bit. Just off the tip of this lineup is the spot in the sky where the Sun will stand on the summer solstice in June.

The brightest of these three stars is known as Tejat. It's more than 200 light-years away. Yet despite that great distance, it's visible to the unaided eye because it's a stellar giant. It's nearing the end of its life, so it's puffed up like a big balloon -- it's perhaps a hundred times wider than the Sun. That's also made it about 1500 times brighter than the Sun.

To the right of Tejat is Propus, a star that's even bigger and brighter, and about half-again as far from Earth. And the star to its right, at the very foot of Gemini, doesn't have a proper name. Instead, it's designated with the numeral "1" -- 1 Geminorum. It's just a whisker away from where the Sun will stand at the summer solstice -- six months from now.


Script by Damond Benningfield, Copyright 2010


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