Alpha Crucis, brightest star in the southern constellation Crux (the Southern Cross) and the 13th brightest star in the sky. Alpha Crucis is about 320 light-years from Earth. It is a multiple star system consisting of three B-type stars, the spectroscopic binary α1 and α2, that are of roughly the same brightness and are close enough together to appear as one star to the naked eye. The stars of α1 orbit around each other every 76 days, but it takes α1 and α2 about 1,500 years to orbit each other.