Many spirals have a halo of stars and star clusters arrayed above and below the disk. Our Milky Way is a spiral, as is the rather close-by Andromeda Galaxy. Spirals are large rotating disks of stars and nebulae, surrounded by a shell of dark matter. Spiral galaxies like the Milky Way are observed as two basic types. A normal spiral, such as the nearby Andromeda galaxy, has a spherical bulge of stars at its center. The other type is the barred spiral, which has an elongated central bulge called a bar. Although a couple of dozen minor galaxies lie closer to our Milky Way, the Andromeda galaxy is the closest major galaxy to ours. Excluding the Large and Small Magellanic Clouds, which can’t be seen from the northern latitudes. The Andromeda galaxy,
