M45, also called The Pleiades, is a cluster of bright, hot, young blue stars about 425 light years from earth. They are believed to have formed about 100 million years ago, making them quite young in astronomical perspective. They appear to the naked eye from earth as a tight group of stars above the horns of Taurus the bull.

The wisps of blue surrounding the brightest stars of the Pleiades cluster are part of a cloud of interstellar dust that the Pleiades are currently moving through. The intense energy given off by the stars makes the dust glow. This phenomenom is called reflection nebulosity.

In Greek mythology, the Pleiades were seven sisters, daughters of Atlas and Pleione. This photo shows the stars representing the seven sisters - Maia, Electra, Taygete, Alcyone, Celaeno, Sterope and Merope. The parents, Atlas and Pleione, are just above this field of view on the left. You can see some of the reflection nebulosity surrounding Atlas near the top left corner of this photo.

If the pattern of these stars looks vaguely familiar, take note that the Japanese name for the Pleiades is "Subaru".