Pegasus, the flying horse:

An ancient constellation who was part of the story of Andromeda and Perseus. It was told that Pegasus was born when the hero Perseus cut off the head of Medusa and some of the blood fell into the sea. Out of the seafoam flew the mythical horse Pegasus. Pegasus was then ridden by Perseus as he rescued Andromeda. Later Pegasus became part of the legend of the hero Bellerophon, who attempted to fly him to Olympus. Zeus was offended by his actions and sent a gadfly to sting Pegasus, who bucked, thus throwing the hero off. The constellation of Pegasus is composed primary of the four stars known as the "Great Square", these stars comprise the body of the horse. Other stars extend off of the square creating the neck and head, and front legs. Most pictures of the constellation show only the front part of the horse and he is pictured upside down in the sky. Pegasus can be found south the the bright constellation of Cassiopeia, and east of the asterism known as the "Summer Triangle".