M45, the Pleiades, is a beautiful open cluster in Taurus surrounded by reflection nebulosity. The cluster has been known since ancient times and contains six bright stars that can easily be seen with the unaided eye, and 500 stars total, most too faint to be seen. The blue nebulosity is visible by starlight reflected off of dust in space. The cluster is located about 440 light years from the Earth and is estimated to be about 100 millions years old.