Sister planet points to Summer Triangle
Thursday, November 24, 2005
Looking West-Southwest Shortly After Sunset
There are 88 "official" constellations, whose boundaries were drawn by the International Astronomical Union in the first part of the 20th century. But there are also "asterisms" -- not official constellations -- simply star patterns, which have endured because they're so noticeable. One of the most prominent asterisms visible during the Northern Hemisphere summer months is called the Summer Triangle. It consists of three bright stars in three different constellations -- Vega in the constellation Lyra the Harp, Deneb in the constellation Cygnus the Swan, and Altair in the constellation Aquila the Eagle. Those of us in the north can see it now, high in the west-southwestern sky. It's big, so don't look for a tiny pattern. You can use our sky's brightest object, the planet Venus, to help you find the star Altair. Altair, now located to the upper right of Venus, can be recognized because of the company it keeps: there's a dimmer star on either side of bright Altair.