You’ve probably never seen two donkeys perched on the back of a crab. Unless, that is, you’ve spent much time looking at the stars. Two faint stars in Cancer have names that mean the northern and southern donkeys — Asellus Borealis and Asellus Australis. They’re on opposite sides of the crab’s back. They flank the constellation’s most famous member — a star cluster known as both the manger and the beehive.
The star names come from Greek mythology. The donkeys carried gods who were involved in a war between two sets of gods — those of Olympus, and their predecessors, the Titans.
The northern donkey is about 180 light-years away. It’s a little more than twice the size and mass of the Sun. But it’s billions of years younger than the Sun.
The southern donkey is a little closer — about 130 light-years. It appears to consist of more than one star. The main star is bigger and heavier than the Sun, and about half the Sun’s age. It’s nearing the end of its life, so it’s puffed up to become a giant — a stage in life that awaits the Sun in several billion years.
Cancer is in the east at nightfall. Pretty much everything in the constellation is faint, so you need a dark sky to see much. A moonless night like tonight is a good time to look. The Beehive star cluster looks like a hazy patch of light. The donkeys flank it — the northern one to the left, and the southern one to the right.
Script by Damond Benningfield