Cassiopeia
Constellation · The Queen
Cassiopeia is a bright “W” of five stars on the opposite side of Polaris from the Big Dipper. In Greek myth she was a vain queen who boasted about her beauty.
- A “W” or “M”Shape
- Tycho’s Supernova (1572)Famous for
- Cassiopeia A remnantHidden inside
Take a closer look
The queen’s punishment
In Greek myth Cassiopeia’s boasting angered the sea god Poseidon, who sent a monster to attack her kingdom. Her daughter Andromeda was chained to a rock until the hero Perseus rescued her. As punishment, the queen circles the pole on her throne, spending half the night upside down.
Cassiopeia A up close
Cassiopeia A is one of the youngest remains of an exploded star in our galaxy. Its light reached Earth around 1680, yet nobody clearly recorded it – thick dust probably hid the flash. X-ray telescopes show clouds of silicon, sulphur and iron flung out from the star’s insides.
Hop to Andromeda
The deeper “V” of Cassiopeia’s W points roughly towards the Andromeda Galaxy. On a dark night it looks like a faint oval smudge to the naked eye. Its light set off about 2.5 million years ago, making it one of the most distant things you can see without a telescope.
How we found out
- 1572
Tycho Brahe sees a brilliant “new star” in Cassiopeia – a supernova. It shows that the heavens are not unchanging, a shocking idea at the time.
- 1947
Radio astronomers detect Cassiopeia A, the remains of another exploded star and one of the strongest radio sources in the sky.
How can you use Cassiopeia to find the North Star?
Polaris sits roughly halfway between Cassiopeia and the Big Dipper. When one is low, the other is high.
See it yourself
Northern Hemisphere: look for a big “W” in the north. It never sets for people north of about 35° latitude.
From the encyclopedia
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