Antares, the brightest star in the constellation Scorpius. The star has a red color like that of the planet Mars. This color is due to the star's relatively low surface temperature (about 5,500 F. [3,040 C], as compared to 11,000 F. [6,100 C] for the sun's surface). Antares was named for its color; it means "rival of Mars" (Ares is the Greek name for Mars). Antares is about 520 light-years from the earth. Its brightness is due to its large sizeit is about 350,000,000 miles (560,000,000 km) in diameter. It is one of the largest stars known and belongs to a class of stars called supergiants. It is a variable star, with a magnitude of 0.92 at maximum brightness. Antares has a much hotter, smaller, faint blue companion star.