Seven Sisters: Pleiades
The Seven Sisters, also called the Pleiades or M45, is an open star cluster located about 400 light years away towards the constellation Taurus. It is about 13 light years across and is one of the brightest and closest star clusters to us.
The cluster contains over 3000 stars, most of which are considered middle aged. Surrounding the brighter stars are reflection nebulae, gas and dust reflecting the light from the stars. Also buried in the cluster are faint, low mass brown dwarf stars.
Image from National Geographic, information from NASA.