Pegasus, the Flying Horse

The brightest star in the Great Square — Alpheratz — isn't in the constellation Pegasus. It's in Andromeda, which is just northeast of Pegasus. It's part of the ancient sky picture that we know as Pegasus. But when astronomers drew the official boundaries for the constellations, this star was placed just across the line in Andromeda.

The brightest star in the constellation Pegasus is called Markab, which means "the saddle." It's at the southwestern corner of the Great Square.