Hunting Orion: Zeta Orionis

Orion constellation is one of the brightest and best known constellations in the night sky. It lies on the celestial equator.

Orion has been known since ancient times. The constellation is also known as the Hunter, as it is associated with one in Greek mythology. It represents the mythical hunter Orion, who is often depicted in star maps as either facing the charge of Taurus, the bull, pursuing the Pleiades sisters, represented by the famous open cluster, or chasing after the hare (constellation Lepus) with his two hunting dogs, represented by the nearby constellations Canis Major and Canis Minor.

The constellation Orion contains two of the ten brightest stars in the sky – Rigel (Beta Orionis) and Betelgeuse (Alpha Orionis) – a number of famous nebulae – the Orion Nebula (Messier 42), De Mairan’s Nebula (Messier 43) and the Horsehead Nebula, among others – the well-known Trapezium Cluster, and one of the most prominent asterisms in the night sky – Orion’s Belt.

Zeta Orionis

Alnitak, designated Zeta Orionis (ζ Orionis, abbreviated Zeta Ori, ζ Ori) and 50 Orionis (50 Ori), is a multiple star several hundred parsecs from the Sun in the constellation of Orion. It is one of the three main stars of Orion's Belt along with Alnilam and Mintaka.  It is very difficult not to see Orion from most of the northern hemisphere in the south-western sky during the winter months, or from the southern hemisphere during the summer time. This is because the constellation itself is situated on the celestial equator, meaning half of it is located in the northern sky and the other half in the south sky, making Orion visible from all places on Earth except near the poles. The asterism that most people first notice when viewing Orion is the sloping diagonal line of three bright stars which represent the Hunter’s belt. For northern observers, Alnitak is the star located furthest east in the Hunter’s Belt, and the one that is nearest the horizon when the constellation is upright.

Quick Facts

Name:  Alnitak

Object:  Star -- Super Giant

Distance: 800 light years

Brightness: 10,000 times greater than the Sun

Surface Temp: 60,000 F

Color: White-blue

Mass: 20 x the mass of the Sun