Cassiopeia, the queen

Cassiopeia's five brightest stars make a W, or an M, depending on the time of night. From mid-northern latitudes the queen circles the pole and never sets.

Where is it from where I am?

How to spot it: Five bright stars in a W (or M) shape. Source (opens in a new tab)

The W

The five brightest stars (opens in a new tab) form a W that Aratus compared to a key or a folding door. Schedar takes its name from the Arabic for "the breast"; Caph from the Arabic for "stained hand", a hand tattooed with henna. In myth she is the boastful queen of Ethiopia, mother of Andromeda.

Tycho's Star

In November 1572 a new star appeared in the W (opens in a new tab). Tycho Brahe published a treatise on it the next year. It reached magnitude −4, as bright as Venus, and stayed visible to the naked eye for more than a year. It was a supernova, an exploding star.

Cassiopeia A

Another explosion here went unrecorded. Cassiopeia A (opens in a new tab), about 11,000 light-years away, is the youngest supernova remnant known in the Milky Way; its light reached Earth some 300 years ago. Chandra's X-ray images show its shock wave accelerating particles to enormous energies.

Where on Earth, and when

The whole key pattern rises from anywhere north of about 26°S.

South of about 33°S, none of it rises.

North of about 33°N, the whole key pattern never sets.

Its middle climbs at least 20° high, the finder's threshold for a suggestion, from anywhere north of about 9°S.

It is highest in the evening sky, at about 9 p.m. local time, in mid-November, from either hemisphere, wherever it rises. With daylight saving time, that is nearer 10 p.m. on the clock.

Worked out by this site from the Bright Star Catalogue, for a flat, clear horizon. Hills, buildings, haze and city light all cut into this; the air also lifts objects near the horizon by about half a degree. For your own place and night, use the sky finder.