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What Is the Legend of the Constellation Cassiopeia?

Cassiopeia is a northern hemisphere constellation situated between the constellations Perseus and Cepheus. She was one of the constellations originally listed by the Greek astronomer Ptolemy. Cassiopeia is a northern circumpolar constellation, which means it can be seen all year. When Cassiopeia's main stars are joined up, it looks like a "W" or "M," depending on its location. In Greek mythology, Cassiopeia was the queen of Aethiopia and the wife of King Cepheus. According to the legend the mythical queen enraged the god of the sea, Poseidon, with her bragging and almost lost her daughter Andromeda.

Bragging Beauty
- As Queen Cassiopeia walked along the shores of the sea with her daughter Andromeda, she saw beautiful Nereids, or sea nymphs, below the water. When Cassiopeia saw the Nereids she boasted that she was more beautiful than they. Poseidon loved the nymphs, who were his handmaidens. The sea nymphs became upset and cried to Poseidon. Poseidon, offended, erupted from the waters. He declared he would punish Cassiopeia by flooding and ravaging Aethiopia with storms unless she sacrificed her daughter to Cetus, the sea monster.
The Sacrifice
- Cepheus and Cassiopeia realized the only way to save their land was to sacrifice Andromeda to the sea monster. Andromeda was taken to the shore and chained to the cliffs. The waters churned and Cetus came up from the sea to eat Princess Andromeda.
Perseus Saves Andromeda
- Perseus, the son of Zeus, watched Andromeda's plight from afar. Riding Pegasus, his winged horse, he appeared as Cetus was about to eat Andromeda. He slew the monster by showing it the head of Medusa, a gorgon he had recently slain. When Cetus looked at Medusa, he turned to stone. Perseus rescued Andromeda and the two were married. They became the ancestors of Hercules and their descendants started the Persian race.
Cassiopeia's Constellation
- Today Cepheus, Andromeda, Perseus, Cetus and Cassiopeia all share the sky as constellations. The legend of Cassiopeia explains why she is sometimes seen as an "M" instead of a "W." As punishment for her vain boasting, she sometimes hangs upside down. This position of humility is also a warning to others not to brag.

Astronomy