Observations: AstronomyCast Globular Cluster

Globular clusters are spherical collections of stars that orbit a galactic core as a satellite. Globular clusters are very tightly bound by gravity, which gives them a spherical shape and relatively high stellar densities toward their centers. These globular clusters are common; there are about 150 to 158 known globular clusters in the Milky Way, with more left to be discovered. Other galaxies have many more clusters than even the Milky Way. The Andromeda galaxy has about 500 and galaxy M87 has as many as 13,000. Although it appears that globular clusters seem to have some of the first formed stars in the galaxy, little is known about their role in galactic evolution.