This month's star is Alkaid

This month look for the star Alkaid in Ursa Major. Alkaid is known to astronomers as Eta Ursae Majoris and it’s located at the end of the Big Dipper’s handle. In Arabic, Alkaid means “the leader”. Its name is a reference to the stare being the lead daughter (the three stars of the handle are sisters) at a funeral bier. If you know someone who is 100 years old this year, then Alkaid is his or her birthday star because the light of Alkaid you see tonight left in 1915.

Alkaid is a big star that’s four times hotter then the sun and 700 times brighter. It’s hotter and brighter because it has a mass six times greater than our sun’s. Alkaid’s greater mass creates intense pressure that’s crushing its core. The extra compression heats up the core and increases its rate of fusion. On the down side, that extra mass will burn out the star far sooner than our sun.

The Big Dipper is not a constellation. Rather, it’s an asterism, or popular pattern of stars. This means the pattern is not officially recognized by professional astronomers. The Big Dipper is part of a much larger constellation called Ursa Major or the Big Bear. The dipper portion of Ursa Major just represents the bear’s body and a very long tail. The rest of Ursa Major is fainter and not as well known. However, in dark skies you can make out three legs, head, and snout of the bear.   

Look for Alkaid tonight almost overhead in the north during June.