Omega Centauri, also known as NGC 5139, is the largest and brightest globular cluster in the Milky Way, containing about 10 million stars. It is located approximately 15,800 light-years away in the constellation Centaurus.
Source: noirlab.edu
21/02/1996

Pictured above is the largest ball of stars in our Galaxy. About 10 million stars orbit the center of this globular cluster - named Omega Centauri - as this giant globular cluster orbits the center of our Galaxy. Recent evidence indicates that Omega Centauri is by far the most massive of the about 160 globular clusters in the Milky Way. The stars in globular clusters are generally older, redder and less massive than our Sun. Studying globular clusters tells us about the history of our Galaxy and the age of the universe.