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Location: Northern Hemisphere
Right Ascension: 01h
Declination: +60º
Source: Greek mythology. The constellation was also identified by the Egyptians (associated with an evil god), the Chinese (a charioteer), and the Celts (home of the king of the Fairies).

The story behind the name: Cassiopeia is named after the queen of a country on the northern coast of Africa, Aethiopia (not modern Ethiopia). She boasted that she and her daughter Andromeda were more beautiful than the Nereids, the 50 sea nymph attendants of Thetis, the sea goddess, and Poseidon, the sea god. Thetis, and Poseidon's wife Amphitrite (an alternate sea goddess), were also Nereids, so Cassiopeia's boast was an insult to the gods. The Nereids begged Poseidon to punish Cassiopeia. Poseidon sent a flood carrying a sea monster to destroy the kingdom. Cassiopeia's husband, King Cepheus consulted an oracle, who told him that the only way to appease Poseidon and stop the monster was to sacrifice Andromeda. Andromeda was chained to a sea cliff to be eaten by the monster. She was rescued by the hero Perseus who had seen her chained to the cliff and had fallen instantly in love with her. Perseus was returning from carrying out his oath to kill the Gorgon, Medusa. Perseus offered to kill the sea monster and rescue Andromeda in return for her hand in marriage. Cepheus and Cassiopeia agreed reluctantly. They had already agreed to marry her to Cephus's uncle (his father's twin brother Agenor), and once she had been rescued, they tried to break their promise to Perseus.

Johannes Hevelius' Cassiopeia from Uranographia (1690)

Andromeda wanted to keep their promise and insisted that the wedding be held immediately. In some versions of the myth, Cassiopeia summoned Agenor, who rushed into the wedding party with armed men. Perseus fought off a number of them but was greatly outnumbered. He picked up Medusa's head (which he was bringing back as proof that he killed her) and when his attackers looked at it, they turned to stone. Poseidon is supposed to have set images of Cepheus and Cassiopeia in the sky. As a punishment for her treachery, her constellation (a zig-zag shape like an "M" or "W") is supposed to represent Cassiopeia either chained to her throne (in an ironic reference to her daughter's ordeal) or stuffed into a basket. Because the constellation is in a circumpolar position (meaning that it seems to revolve centered around the pole star, Polaris), Cassiopeia is at times suspended upside down in the sky in a very undignified position.

Introduction to Constellations | Constellation Sources | Constellations Index

Objects observed by Chandra in Cassiopeia: