The Summer Triangle & Perseids
A well-known asterism outshines a favorite meteor shower that has to compete with a bright moon this year.
The Perseid meteors are spoiled by a nearly full moon but the Summer Triangle never disappoints. Use it to find the Milky Way and the most beautiful double cluster.
The year 2005 was spectacular for the Perseid meteors. Because of its strength and the warm summer nights, the peak of the Perseid meteor shower on August 12 is usually a heavily witnessed event. But for 2006, even if you are out with the intent of seeing some shooting stars, you might be out of luck. The moon, being just past full, will be big and bright and will wash out the fainter meteors. But it is definitely still worth a look, especially in the early evening before the moon rises. You could even catch a fireball or two.
The Summer Triangle is positioned right overhead all summer long. Its corners are marked by three bright stars from different constellations. The easiest way to find it is to head outside at sunset on a clear summer night and wait for it to get dark. For August 2006, the first "star" you will see in the sky is not a star at all, but Jupiter, sitting low in the south. But if you look straight overhead, the first real star to appear in the night sky is Vega in the constellation Lyra the Harp, one of the corners of the Summer Triangle.
The next two bright stars to appear form the other corners of the Summer Triangle. Deneb, in the constellation Cygnus the Swan, is to Vega's northeast, and Altair, in the constellation Aquila the Eagle, is to Vega's southeast. Voila! The Summer Triangle.
Now wait until the sky gets dark. Really dark. It helps if you live away from the light pollution of cities. Look at the center of the Summer Triangle. Flowing right behind Deneb and through the goalposts of Vega and Altair is the Milky Way - our home galaxy. If you have binoculars or a telescope, sweep the area and look at the countless stars.
Now trace out the constellation of Cygnus the Swan. Starting from Deneb, draw a line with your eyes across the stars that head between the other two Summer Triangle stars. You should see some brighter stars in a line, and two bright stars on either side, forming a lowercase "t" or a cross. Cygnus is sometimes called the Northern Cross. Once you find the cross shape, look at the star at the foot of the cross, nearly in the center of the Summer Triangle. This is Albireo. Train your binoculars or a small telescope on it to find one of the most beautiful double stars in the sky. The blue and yellow stars are about 380 light-years away from Earth.
