(Alpha Scorpii) Antares (meaning Rival of Mars) is the brightest star in Scorpius, one of the constellations in the zodiac. Antares is a M1.5Iab variable red supergiant star… that is about 520 light-years from Earth and is about 230 times as big as the Sun. This incredibly massive, old, low-temperature (3500 K) star is the 15th brightest star in the sky; it has a visual (apparent) magnitude of +0.96 (var.) and an absolute magnitude of -5.2.