Since Poseidon thought that Cassiopeia should not escape punishment, he placed her in the heavens tied to a chair in such a position that, as she circles the celestial pole in her throne, she is upside-down half the time.
Since Poseidon thought that Cassiopeia should not escape punishment, he placed her in the heavens chained to a throne in such a position that referenced Andromeda's ordeal. As she circles the celestial pole in her throne, she is upside-down half the time.