The star Alpha Scorpii, an M1 supergiant over 10 000 times as luminous as the Sun and with a diameter about 400 times the Sun’s. It is a semiregular variable, ranging between magnitudes 0.9 and 1.2 with a period of about 5 years. Antares lies 554 l.y. away. It has a B3 dwarf companion of magnitude 5.4 with an orbital period of about 1200 years. The name Antares is Greek, and is usually translated as ‘rival of Mars’, because of its strong red colour, but sometimes as ‘like Mars’.