Orion's Belt


Orion's Belt or the Belt of Orion, also known as the Three Kings or Three Sisters, is an asterism in the constellation Orion. It consists of the three bright stars Alnitak, Alnilam and Mintaka.
Looking for Orion's Belt in the night sky is the easiest way to locate Orion in the sky. The stars are more or less evenly spaced in a straight line, and so can be visualized as the belt of the eponymous hunter's clothing. They are best visible in the early night sky during the Northern Winter/Southern Summer, in particular the month of January at around 9:00 pm.

Component stars

The names of the three stars come from Arabic. Alnilam means "string of pearls" or is related to the word nilam ; spelling variants include Alnihan and Alnitam,, with all three evidently being mistakes in transliteration or copy errors.

Alnitak

Alnitak is a triple star system at the eastern end of Orion's belt and is 1,260 light-years from the Earth. Alnitak B is a 4th-magnitude B-type star which orbits Alnitak A every 1,500 years. The primary is itself a close binary, comprising Alnitak Aa and Alnitak Ab. Alnitak Aa is estimated as being up to 28 times as massive as the Sun, and to have a diameter 20 times greater. It is the brightest star of class O in the night sky.

Alnilam

Alnilam is a supergiant, approximately 2,000 light-years away from Earth and magnitude 1.70. It is the 29th-brightest star in the sky and the fourth-brightest in Orion. It is 375,000 times more luminous than the Sun. Its spectrum serves as one of the stable anchor points by which other stars are classified.

Mintaka

Mintaka is 1,200 light-years away and shines with magnitude 2.21. Mintaka is 90,000 times more luminous than the Sun. Mintaka is a double star. The two stars orbit around each other every 5.73 days.

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