"constellation of Cassiopeia"

In Greek mythology, Cassiopeia was the beautiful but vain queen of Ethiopia. Her boasts led Poseidon to threaten the whole country with a sea monster, who was to be appeased by the sacrifice of daughter Andromeda until Perseus saved her.

Poseidon punished Cassiopeia in any case.  He tied her to a chair in the heavens, in such a position that she would spend half of each year upside down.  So it is with the constellation named after her: it is sometimes upside down.