Orion Constellation

Orion the Hunter is, for many people, the very first constellation they learn to recognize: a bold, boxy figure marked by three evenly spaced stars forming his belt, with a bright red shoulder and an even brighter blue foot. Visible from virtually every inhabited place on Earth, Orion represents a mighty hunter of Greek myth, forever chasing (or fleeing) the scorpion that killed him, and his belt and sword point toward some of the richest star-forming regions visible from our planet.

Orion at a Glance

• AbbreviationOri
• Genitive FormOrionis
• MeaningThe Hunter
• Constellation FamilyOrion family
• Area594 sq. degrees (26th largest of 88)
• Right Ascension4h 42m – 6h 25m
• Declination+22.9° to -10.9°
• Brightest StarRigel (magnitude 0.13)
• Best Evening ViewingJanuary, visible 85°N to 75°S

Mythology and History

Orion's myths vary by source, but most describe him as a supremely skilled hunter, sometimes said to be the son of the sea god Poseidon, who boasted he could kill any animal alive. That arrogance drew the attention of Gaia or Artemis, who sent a scorpion to sting him fatally — the same scorpion now represented by the constellation Scorpius. Zeus placed both figures in the sky but on opposite sides, so that Orion sets below the horizon just as Scorpius rises, eternally fleeing his killer. Orion was one of the 48 constellations described by Ptolemy in the 2nd century AD, and because it straddles the celestial equator almost perfectly, it is one of the few constellations visible, at least in part, from every inhabited continent on Earth.

Notable Stars in Orion

Despite its Bayer designation as "Beta," Rigel is actually the brightest star in Orion, a blue supergiant roughly 860 light-years away shining at magnitude 0.13 with a luminosity tens of thousands of times that of the Sun. Betelgeuse, the constellation's other famous star, is a massive red supergiant marking the hunter's shoulder; it varies noticeably in brightness and has swollen so large that, were it placed at the center of our solar system, its surface would extend past the orbit of Jupiter. Astronomers expect Betelgeuse to end its life in a supernova explosion at some point in the next 100,000 years — a cosmic blink of an eye.

Deep-Sky Objects

Orion's sword, hanging below his belt, contains the Orion Nebula (M42), one of the most spectacular sights in the night sky and visible to the naked eye as a fuzzy patch even without a telescope. Inside this glowing cloud of gas and dust, new stars are actively being born, including the four hot young stars of the Trapezium Cluster at its core. Nearby, the Horsehead Nebula is a dark pillar of dust silhouetted against a glowing red backdrop — one of astronomy's most photographed objects, though genuinely difficult to see without specialized equipment.

• Orion Nebula (M42) — a spectacular stellar nursery visible to the naked eye as the fuzzy middle 'star' of Orion's sword, one of the brightest and most-photographed nebulae in the sky
• De Mairan's Nebula (M43) — a smaller companion cloud of glowing gas directly adjacent to the Orion Nebula
• Horsehead Nebula — a dark, dust cloud silhouetted against a glowing red backdrop, one of the most photographed — and hardest to see visually — objects in astronomy

Neighboring Constellations and How to Find It

Orion is almost impossible to miss during winter evenings: look for three bright stars in a short, straight, evenly spaced line — the belt — flanked by red Betelgeuse above and blue-white Rigel below. It reaches its highest point around January and, sitting nearly on the celestial equator, is visible from nearly everywhere on Earth at some point in the year. Orion borders Gemini, Taurus, Eridanus, Lepus, and Monoceros.

Orion is also associated with the Orionids and Chi Orionids meteor showers, visible to observers who track where these annual displays radiate from.