The star α Centauri, also known (especially to navigators) as `Rigel Kentaurus' or `Rigil Kent'. With an apparent visual magnitude of −0.28 it is the third brightest star in the sky. A telescope, however, shows it to be a binary system, the components being a yellow G2V star, α Cen A, of magnitude −0.01, and an orange K1V star, α Cen B, of magnitude 1.35.