When Pegasus is in the sky its great square dominates the area. The constellation is unusual in that it shares one of its brightest stars. Alpheratz, at the top left of the square, is actually Alpha Andromeda. Alpha Pegasus is Merkab, at the opposite corner of the square. For all its size Pegasus is extremely sparse in deep sky objects. Its one Messier onject, M15, lies on the far right edge of the image.