Messier 30 — Globular Cluster in Capricornus

M30 is a globular cluster in the constellation Capricornus, located about 26,100 light-years from Earth. It spans approximately 93 light-years in diameter and contains several hundred thousand stars. The cluster has undergone a process called core collapse, in which gravitational interactions have caused stars to migrate inward, creating an extremely dense stellar core. Only about 20% of the Milky Way's globular clusters have undergone core collapse. M30 is estimated to be about 12.9 billion years old, nearly as old as the universe itself. It is moving toward us at about 182 km/s.

Located about 3 degrees east-southeast of Zeta Capricorni. In binoculars, M30 appears as a small, faint fuzzy spot. A 4-inch telescope at 100x shows a compact, bright core surrounded by a fainter halo. An 8-inch or larger telescope at 150-200x begins to resolve individual stars in the outer regions, with the core remaining an intense, unresolved blaze. Chains of resolved stars extend from the cluster's periphery. M30 is one of the more southerly Messier objects and is best observed from August through October. From mid-northern latitudes it never rises very high, so steady seeing is helpful.

Discovered by Charles Messier on August 3, 1764. William Herschel first resolved it into stars in the 1780s. In the 20th century, detailed photometric studies revealed M30 as one of the most metal-poor globular clusters known, indicating it formed very early in the Milky Way's history. Hubble Space Telescope observations confirmed its core-collapsed structure and revealed unusual populations of blue straggler stars.