Antares (ăntârˈēz) [key], brightest star in the constellation Scorpius; Bayer designation Alpha Scorpii; 1992 position R.A. 16h27.6m, Dec. - 26°22−. A red supergiant of spectral class M1, Antares has an apparent magnitude of about 0.9, making it one of the 20 brightest stars in the sky. Its name is from the Greek meaning "rival of Mars," referring both to its color and to its brightness. Antares is a binary star and a semiregular variable, with magnitude ranging from 0.86 to 1.02. Its distance from the earth is about 520 light-years.