Omega Centauri: A Bright Old Star Cluster

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Globular star cluster Omega Centauri holds about 10 million stars that are much older than the Sun in a space about 150 light-years across. It is also known as NGC 5139. It lies about 15,000 light-years away and is the largest and brightest of about 200 known globular clusters that orbit the halo of the Milky Way.

Unlike many star clusters, Omega Centauri shows different groups of stars with a range of ages and chemical makeup. In fact, Omega Centauri may be the remnant core of a small galaxy that merged with the Milky Way. The cluster has a yellowish color, and its red giant stars are easy to spot in a clear telescope view. Over about twenty years of observations with the Hubble Space Telescope, scientists have found evidence for a massive black hole near the center of Omega Centauri.

APOD has updated its email for image submissions. See APOD Submissions. APOD's main NASA site is moving from apod. nasa.gov to science. nasa.gov/ apod. Tomorrow's picture: Reflections on a starry night