Milky Way galaxy. Computer artwork of the Milky Way galaxy, which contains our solar system, with its four arms labelled. Our solar system (bottom, labelled) is located on an arm arc between two complete arms (Perseus and Carina-Sagittarius). The other two arms are Crux-Scutum and Norma. The Milky Way is a spiral galaxy. It has a nucleus (yellow) of old stars at its centre, which has a bar (white) of similar stars passing through it. Around this nucleus, but 10,000 to 16,000 light years away, is a bright 'molecular ring' (blue) of young hot stars and star forming regions. The spiral arms extend outwards from this ring. The Milky Way is thought to be 100,000 light years across, and have hundreds of billions of stars.