Pleiades star cluster (M45, NGC 1432). North is at top. This cluster is about 30 light years wide, and lies 400 light years away in the constellation Taurus. The brightest stars are embedded within streaky reflection nebula, wisps of cold gas and dust which reflect the light of the stars. These are thought to be the remnants of the gas cloud from which the stars formed. The cluster is also known as the Seven Sisters although most people can only see six stars with the naked eye. It actually contains around 500 stars.