NGC 5139: Omega Centauri

Centaurus, a southern constellation named for the mythical half-horse half-man, contains the largest globular cluster corrently observed by mankind. It also includes the star Alpha Centauri, the closest star to our Sun. The globular cluster itself is almost 15,000 lightyears away, and is one of the 150 globular clusters that form a sort of "halo" around our Milky Way galaxy.