Milky Way. Artwork of the Milky Way, our galaxy. The Milky Way is a spiral galaxy which consists of a bright core surrounded by a disk containing long, swirling lanes (arms) of stars. The core of the Milky Way is about 10,000 light years thick and the disk is about 100,000 light years across. The Milky Way is thought to have about 2 million million times as much mass as our Sun. The Sun lies in one of the arms. The Milky Way received its name because it appears as a dim, white, luminous band which stretches across the night sky.