Globular star cluster M22 (NGC 6656), optical image. Globular star clusters are large, densely- packed balls of old stars. M22 is about 97 light years across. At a distance of about 10,400 light years, M22 is among the closest globular star clusters, and is one of the four brightest in the night sky. It is thought to contain over 70,000 stars. M22 is in the constellation Sagittarius. It is one of some 200 globular star clusters that are associated with our Milky Way galaxy.