M45: The Pleiades Star Cluster

Explanation: Perhaps the most famous star cluster on the sky, the Pleiades can be seen without binoculars from even the depths of a light-polluted city . Also known as the Seven Sisters and M45 , the Pleiades is one of the brightest and closest open clusters . The Pleiades contains over 3,000 stars, is about 400 light years away, and only 13 light years across. A prominent telescope and car company has borrowed the star cluster's name. Quite evident in the above photograph are the blue reflection nebulae that surround the brighter cluster stars . Low mass, faint, brown dwarfs have also been found in the Pleiades .