Alcyone, of the Pleiades, is January's Star

This month look for the star Alcyone, the brightest star in the open cluster, the Pleiades. The Japanese name the cluster, Subaru, so look carefully at the next Subaru you see. The symbol on the car is a stylized diagram of the Pleiades star cluster. The Pleiades goes by the names of M-45 and the Seven Sisters (although most people only see six stars without optical aid). The seven sisters were daughters of the titan, Atlas and his wife, Pleione. The names of the six stars most people see, in order of brightness, are Alcyone, Electra, Maia, Atlas, Merope, and Taygeta. The next three fainter stars are named after the their mother and the two remaining sisters, Pleione, Celaeno, and Asterope   The first known mention of the Pleiades was around 1,000 BC by the Greek writer Hesiod.  

In 10X50 binoculars, the brightest portion of the Pleiades occupies about 1/5th of the field of view. When you include the fainter surrounding stars, the Pleiades occupies closer to 1/4th of the field of view. In moderately light polluted skies, I could easily see 20 stars though my binoculars and Alcyone is the brightest Pleiad and located is the center of the star cluster.

The Pleiades are 440 light years away. Therefore, the Pleiades you see tonight existed back in 1575. They formed from the same cloud of dust and gas about 100 million years ago. In time, the stars of the Pleiades will drift a part, as their combined gravity is too weak to hold the cluster together. In long duration exposures, a blue cloud of dust appears surrounding the stars. The stars and bright blue-white frosting makes the Pleiades look like some fantastic piece of jewelry. The cloud however, is not what remains of the dust and gas from which the Pleiades formed. It happens to be a separate cloud that the cluster is currently drifting through.

The Pleiades and Alcyone are visible high in the east on December nights.