Orion, in astronomy, constellation located on the celestial equator. It is one of the most conspicuous and easily recognizable constellations in the entire sky. From ancient times it has been mentioned in the literature of many peoples and is traditionally depicted as the figure of a warrior. Four bright stars form a quadrangle marking his shoulders and feet; brilliant red Betelgeuse (Alpha Orionis) at his right shoulder, Bellatrix (Gamma Orionis) at his left shoulder, and dazzling Rigel (Beta Orionis) at his left foot are all among the 25 brightest stars in the sky, while Saiph (Kappa Orionis) at the right foot is of second magnitude. Three bright second-magnitude stars form a belt almost along the celestial equator; hanging from the belt is a sword of dimmer stars and including the famous Great Nebula (M42). Orion reaches its highest point in the evening sky in late January.