TThis week, track the constellation Cetus, variously called the whale or the sea monster. It is one of the faintest constellations, but it extends across the entire sky, covering approximately 1,230 square degrees, making it the fourth largest of the 88 modern constellations. Although it has no bright stars, there is something hypnotic about tracing its faint outline across the sky.
The diagram shows the view looking south-southeast from London on 17 November at 20:00 GMT. However, the view will not change much throughout the week. Because Whale is located near the celestial equator, it can be seen in the northern and southern hemispheres.
In classical Greek mythology, Keth is a sea monster sent by Poseidon to wreak havoc on the kingdom of King Cepheus and Queen Cassiopeia. To protect his daughter Andromeda, the hero Perseus turned Keith into a stone with the head of the gorgon Medusa.
There really is one true astronomical gem in the constellation: Omicron Ceti or Mira. The brightness of this variable star rises and falls approximately every 330 days. At its weakest, it is invisible to the naked eye. Its brightness is now near its minimum, so stargazers should keep a close eye on it becoming visible again in the coming months.
