Obscure constellation’s name features in Perseus myth as beast denied chance to devour Andromeda
This week presents a good chance to see one of the more obscure autumn constellations: Cetus, the sea monster. Sometimes referred to as a whale, Cetus is part of the myth of Perseus, which includes the other constellations Pegasus, Cassiopeia, Andromeda, and Cepheus.
In the story, Perseus rescues Andromeda from Cetus, after she is chained to the rocks for the monster to devour in the gods’ punishment for Andromeda’s boasts of her beauty.
The chart shows the view looking south from London this evening at 9pm (2100 GMT). Alpha Ceti, also known as Menkar, is the nose of the sea creature; Diphda (Beta Ceti) is also known as Deneb Kaitos, meaning whale’s tail. To find the dim constellation, start by identifying Taurus and Orion.
Extending an imaginary line drawn from Aldebaran down through the body of Taurus, to another line extended through Betelgeuse and Bellatrix, should allow you to converge on Menkar. From there, star-hop around the rest of the constellation.
Cetus is prominent in the southern skies too. From Sydney, Australia, look to the north-west. Cetus is in a part of the sky referred to colloquially as the celestial waters because it contains other water-based constellations such as Pisces, the fish, Aquarius, the water-bearer, and Eridanus, the river.