Astronomy - Orion's belt

Orion's belt

The tight linear grouping of the prominent white stars Alnitak, Alnilam, Mintaka in the constellation of Orion. The names of all three refer to the set: the outer two are named after the "belt" of the Arabs' "Central One" (a mysterious female figure), while Alnilam comes from an Arabic word that aptly means "the string of pearls." The proximity of the three in the sky is an illusion. In fact, the stars at either end of the Belt, Alnitak and Mintaka, are the closest together in space, Alnitak being a little over 800 light-years away, and Mintaka 100 light-years farther off. The central star, Alnilam, is much more distant than either of these, lying on the edge of the Orion Molecular Cloud, more than 1,300 light-years from the Sun. Alnilam is also easily the most massive and luminous of the three stars, so that despite its greater distance it still shines more brightly than its two companions.

Like much of its parent constellation, Orion's Belt is a highly nebulous region of the sky. This is especially true in the direction of Alnitak, where numerous nebular structures are found. The most famous of these is the Horsehead Nebula, a dark cloud that blots out the light from the red-pink streak of IC 424.

Mythology

Greek mythology has several versions of the history of Orion, the gigantic hunter of primordial times. These end in different versions of his death: He challenged the gods, either by attempting to rape Artemis or by claiming that he could kill every wild animal on Earth. Some versions then say Artemis shot him with her arrows; but others say that Artemis or Earth produced a great Scorpion whom he could not defeat and which killed him. The gods raised him and the Scorpion to the skies, as Scorpio/Scorpius. Yet other stories say Orion was chasing the Pleiades.

Sirius, the Dog Star, constitutes Orion's left leg. It is part of Canis Major and has its own mythology. In some myths, it is Orion's hunting dog.