#messier9

Globular clusters: Messier 3, Messier 9 and Messier 15

A globular cluster is a spherical collection of stars that orbits a galactic core as a satellite. Globular clusters are very tightly bound by gravity, which gives them their spherical shapes and relatively high stellar densities toward their centers.

The first known globular cluster, now called M22, was discovered in 1665 by Abraham Ihle, a German amateur astronomer.However, given the small aperture of early telescopes, individual stars within a globular cluster were not resolved until Charles Messier observed M4 in 1764. (To learn more, click here).

Messier 9

Messier 9 is a globular star cluster located about 25,000 light years away towards the center of the Milky Way. Due to its proximity to the Milky Way’s center, the shape of the cluster is slightly deformed from the gravitational pull. The cluster holds over 250,000 stars.

Globular clusters are thought to hold the oldest stars of the galaxy, much older than our Sun, born when the universe was fractionally younger. Their stars have much fewer heavy metals, since these elements form in supernovas and the cores of stars. When the clusters formed, there was much less of these elements around, including carbon, iron, and oxygen, elements key to life on Earth.

M9 Globular Cluster

This is a hubble image of the Messier 9 globular cluster which is approximately 25,000 light years away and is estimated to contain a quarter of a million stars.