The Milky Way has a central bar of stars about 27,000 light-years long, with spiral arms winding outward. The Sun sits in the Orion Arm (or Orion Spur), a minor arm between the larger Sagittarius and Perseus arms, about 26,000 light-years from the galactic center.

The disk of the galaxy is remarkably thin relative to its width — only about 1,000 light-years thick. Surrounding the disk is a spherical halo of old stars and roughly 150 globular clusters, each containing hundreds of thousands of ancient stars.