In Greek mythology, Cassiopea was the wife of Cepheus, king of Joppa (often called Ethiopia). Cassiopea once boasted that she and her daughter Andromeda were more beautiful than the sea nymphs known as the Nereids. The Nereids were so insulted that they asked Poseidon (Neptune), god of the sea, to punish Cassiopea. He responded by sending a flood and a sea monster to devastate the land.
An oracle told Cepheus that the only way he could save his kingdom was by sacrificing his daughter to the sea monster. With a heavy heart, Cepheus decided to do so. He chained Andromeda to a rock in the sea and left her there to be devoured. However, the hero Perseus * saw her and rescued her, and as a reward, Cepheus promised Andromeda to Perseus as his bride. At the wedding, though, Andromeda's uncle Phineus claimed that she had been promised to him. Perseus used the head of the monster Medusa* to turn Phineus to stone and then married Andromeda.
nymph minor goddess of nature, usually represented as young and beautiful
oracle priest or priestess or other creature through whom a god is believed to speak; also the location (such as a shrine) where such words are spoken
When Cassiopea died, Poseidon made her into a constellation in the night sky. To punish her for insulting the Nereids, however, he arranged the constellation so that at times Cassiopea appears to be hanging upside down with her feet in the air.