Messier thirteen

Messier 13 (M13), or the Great Hercules Cluster, is perhaps the most famous globular cluster in the northern sky. It is located at a distance of about 22,200 light-years from Earth and consists of several hundred thousand stars. M13 has a diameter of about 145 light-years, making it one of the largest globular clusters associated with our Galaxy. Like other globular clusters, it is a densely packed sphere of old stars, gravitationally bound to each other. The core of M13 has a very high concentration of stars, making this region extremely dense compared to the outer halo of the cluster. In the center of the cluster, stars can be as close as 0.05 light-years apart—about 10 times closer than the Sun and its nearest neighbor.