Astronomy Picture of the Day

Explanation: Pictured above is the largest ball of stars in our Galaxy. About 10 million stars orbit the centre of this globular cluster - named Omega Centauri - as this giant globular cluster orbits our Galactic centre. Recent evidence indicates that Omega Centauri is by far the most massive of the about 150 known globular clusters in the Milky Way. Omega Centauri, catalogued as NGC 5139, spans about 150 light years across, lies about 15,000 light years away, and can be seen without visual aid toward the constellation of Centaurus. The stars in globular clusters are generally older, redder and less massive than our Sun. Studying globular clusters tells us not only about the history of our Galaxy but also limits the age of the universe.