Centaurus is one of the largest constellations in the Southern Hemisphere. Its brightest star, Alpha Centauri, is the third brightest star in the heavens and a member of a triple star system that includes Proxima Centauri. At a distance of 4.3 light years, Proxima Centauri is the nearest known star to the Earth, other than the Sun. The constellation also contains the brightest and nearest of the globular clusters, known as Omega Centauri, a system of about 50,000 stars at a distance of 20,000 light years.