Omega Centauri, NGC 5139

Omega Centauri, NGC5139, a globular cluster in the constellation Centaurus, as seen by the CTIO 4-meter telescope in 1975. Only 17000 light-years away and containing more than one million stars within its 150 light-year diameter, Omega Cen is visible with the naked eye from the southern hemisphere and the southern part of the northern hemisphere. At the crowded center, stars may be as close together as one tenth of a light-year (note that our own nearest star is 4.3 light-years away).