What is the largest globular cluster in the Milky Way?

The largest globular cluster in the Milky Way is Omega Centauri. Also catalogued as NGC 5139, it is an enormous, densely packed sphere containing roughly 10 million stars. The cluster lies about 17,700 light-years from Earth in the constellation Centaurus and is bright enough to be visible without a telescope from suitable southern locations.

Omega Centauri has an unusual history. Ancient observers listed it as a star, and Edmond Halley described it as a nebula in 1677. John Herschel recognized its true nature as a globular cluster in the 1830s. Unlike most globular clusters, Omega Centauri contains stars with several different ages and chemical compositions, suggesting that it may be the surviving core of a dwarf galaxy that the Milky Way absorbed long ago.

It is often confused with M13, M22, or 47 Tucanae, all impressive globular clusters but smaller than Omega Centauri. Its size, brightness, complex stellar populations, and possible intermediate-mass black hole make it one of the Milky Way’s most important laboratories for studying ancient stars and galactic mergers.