Steamboat Springs Two of my favorite constellations of late summer are two of the smallest in the whole sky. They aren't big and showy star patterns with lots of bright stars like Orion or the Big Dipper. Instead, they are small, compact and easy to spot only because of their charming, distinctive shapes. They are Delphinus the Dolphin and Sagitta the Arrow.
The Dolphin and the Arrow are neatly tucked under the wing of the nearby constellation Aquila the Eagle, marked by its bright star Altair. To locate these two tiny constellations, go outside at about 11 p.m. and look high in the eastern sky. You should spot the three bright stars marking the corners of the Summer Triangle: Vega, nearly straight up; Deneb, fainter and to the northeast; and Altair, to the southeast of Vega. Just east of Altair you can spot the small diamond-shaped pattern of Delphinus. The four main stars form the head and body of the little dolphin and a fifth star, off to the lower right, marks his tail. You can just about cover the entire constellation of Delphinus with your thumb held at arms length.
Delphinus the Dolphin long has been known as "Job's Coffin," suspended halfway between earth and heaven, but it doesn't take a lot of imagination to see a little dolphin jumping up out of the celestial sea.
Just west of Delphinus and equidistant from Delphinus and Altair is Sagitta the Arrow. Look for four stars in a row with the last two sitting close together, side by side. This pair marks the feathers, or fletching, on the end of the arrow. This errant arrow probably belongs to Sagittarius the Archer, far to the south. Moving from Delphinus to Sagitta and then continuing in the same direction, you will find a small, fuzzy patch of light sitting in a dark portion of the Milky Way. It also lies on the line connecting the two bright stars Altair and Vega. This is not a constellation but a tiny asterism called Brocchi's Cluster, named for amateur astronomer D. F. Brocchi. If you have a pair of binoculars handy, aim at the fuzzy spot to see why this delightful little asterism is nicknamed "The Coat Hanger." Its 10 stars are arranged in the unmistakable pattern of a coat hanger, complete with hook on top. Once thought to be a cluster of stars moving together through space, astronomers are now convinced the 10 stars are unrelated and this remarkable arrangement of stars is completely by chance.
Jimmy Westlake teaches astronomy and physics at Colorado Mountain College's Alpine Campus. He is an avid astronomer whose photographs and articles have been published on the Web sites of CNN.com, NASA's "Astronomy Picture of the Day," Spaceweather.com, Space.com, Discover.com, and in Sky & Telescope, Astronomy, Night Sky, Discover, and WeatherWise magazines.