Sky Spy: Summer Triangle in view tonight

2013-07-25T00:00:00Z Sky Spy: Summer Triangle in view tonightTim Hunter Special To The Arizona Daily Star Arizona Daily Star

If you follow the moon tonight with binoculars or a small telescope as it rises above the mountains, I guarantee you will have a delightful time watching it slide past the distant mountain peaks.

After the moon has gotten several degrees above the horizon, step back a bit to enjoy the summer triangle of Vega, Altair and Deneb.

These stars are well above the horizon by 9:45 p.m. and can be found by looking above the moon to nearly overhead where there will be Vega in Lyra the Lyre about 80 degrees above the eastern horizon. Below Vega and toward south about 50 degrees above the horizon is Altair in Aquila the Eagle and north (left) of Altair is Deneb in Cygnus the Swan about 55 degrees above the horizon.

These three bright stars form a roughly equilateral triangle known as the Summer Triangle. I always mention them every summer as they are bright, interesting objects.

The stars of the Summer Triangle are all blue or blue-white in color and among the brightest stars in the sky. They are not related to each other, just happening to lie close together from our point of view.

Vega the fifth brightest star in the sky is 25 light years away with a large disk of gas and dust possibly containing planets surrounding Vega.

Altair 17 light years away rotates so fast it is shaped like an egg.

My favorite is Deneb, which is estimated to be roughly 1,425 light years from us. Even so, Deneb is the 19th brightest star in the sky. Deneb is one of the most luminous stars in the entire Milky Way.

Moon Watch

The moon is in a waning (growing smaller) gibbous (more than half lit) phase. Last quarter is next Monday. The moon officially rises at 9:26 p.m. today almost due east.

Contact Tim Hunter at skyspy@azstarnet.com

Copyright 2014 Arizona Daily Star. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

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