Perseus, named after the Greek mythological hero Perseus, is a constellation in the northern sky. It was one of 48 listed by the 2nd-century astronomer Ptolemy and among the 88 modern constellations Perseus rescued the princess Andromeda from Cetus by turning it to stone with Medusa's head. He turned Polydectes and his followers to stone and appointed Dictys the fisherman king. Perseus and Andromeda married and had six children. In the sky, Perseus lies near the constellations Andromeda, Cepheus, Cassiopeia (Andromeda's mother), Cetus, and Pegasus.