Star Tales – Cassiopeia

Cassiopeia was the vain and boastful wife of King Cepheus of Ethiopia, who lies next to her in the sky. They are the only husband-and-wife couple among the constellations. Classical authors spell her name Cassiepeia, but Cassiopeia is the form used by astronomers.

While combing her long locks one day, Cassiopeia dared to claim that she was more beautiful than the sea nymphs called the Nereids. Such hubris by a mortal could not go unpunished and the Nereids went in search of retribution. There were 50 Nereids, all daughters of Nereus, the so-called Old Man of the Sea, and one of them, Amphitrite, was married to Poseidon, the sea god. Amphitrite and her sisters appealed to Poseidon to punish Cassiopeia for her vanity. Bowing to their request, the sea god sent a monster to ravage the coast of King Cepheus’s country. This monster is commemorated in the constellation Cetus. To appease the monster, Cepheus and Cassiopeia chained their daughter Andromeda to a rock as a sacrifice, but Andromeda was saved from the monster’s jaws by the hero Perseus in one of the most famous rescue stories in history.

As an added punishment, Cassiopeia was condemned to circle the celestial pole for ever, sometimes hanging upside down in undignified posture. In the sky Cassiopeia is depicted sitting on her throne, still fussing with her hair.

Cassiopeia, the vain queen seated on her throne, depicted in the

Atlas Coelestis of John Flamsteed (1729).

The constellation of Cassiopeia has a distinctive W-shape made up of its five brightest stars, which writers such as Aratus likened to a key or a folding door. Alpha Cassiopeiae is called Shedir or Schedar, from the Arabic al-sadr meaning ‘the breast’, where Ptolemy said it lay. Beta Cassiopeiae is known as Caph from the Arabic meaning ‘stained hand’, as the stars of Cassiopeia were thought by the Arabs to represent a hand stained with henna. Delta Cassiopeiae is named Ruchbah, from the Arabic for ‘knee’, rukbat. The central star of the W, Gamma Cassiopeiae, is an erratic variable star, given to occasional outbursts in brightness.

Although the W shape of Cassiopeia seems obvious to us, Chinese star charts showed no sign of it. Instead, three stars of the W – Alpha, Beta and Gamma – were part of a group called Wangliang, commemorating a legendary Chinese charioteer of that name; Alpha itself represented his whip. Chinese charts usually show this as a fan-shaped group of five stars, the fourth and fifth members being Eta and Zeta Cassiopeiae. The other two stars of the W (Delta and Epsilon Cassiopeiae) were part of a chain called Gedao running southwards from Iota Cassiopeiae via Theta to Xi or Omicron Cassiopeiae, which represented a mountain path; it was also seen as the banner of Wangliang.

Crossing northern Cassiopeia from present-day Cepheus into Camelopardalis was a chain of stars including Psi Cassiopeiae called Chuanshe, representing guest rooms for visitors. Farther north still were Huagai and Gang, two related groups of stars including Omega and 50 Cassiopeiae that represented the Emperor’s gilded canopy and its support.