Tonight

See Orion’s Belt as a celestial bridge

Orion's Belt: Star chart of large constellation Orion with stars labeled.
Look east in mid-evening in November for the constellation Orion the Hunter. The 3 stars at the midsection of the Hunter are known as Orion’s Belt. The star Mintaka lies on the celestial equator, a line around the entire sky, above Earth’s equator. Hence the legend of Orion’s Belt as a celestial bridge.

Look for Mintaka in Orion’s Belt

See the three stars at Orion the Hunter’s midsection? These stars are Alnitak, Alnilam, and Mintaka. They’re very noticeable and famous in many cultures as Orion’s Belt. To the Aymara people of Bolivia, Peru and Chile, they represent a celestial bridge. And there’s good reason for that. These stars link the sky’s northern and southern hemispheres.

Consider Mintaka, which is the Belt’s westernmost star. It sits almost directly astride the celestial equator: the projection of Earth’s equator onto the stellar sphere.

Where can you find Mintaka and the constellation Orion? In late November, from around the world, Orion rises into your eastern sky around 9 p.m. and climbs highest for the night around 1 to 2 a.m. local time. That’s the time on your clock no matter where you are on the globe.

When dawn is breaking, or about to break, say around 5 to 6 a.m., the Hunter sits low in your western sky.

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Star chart with constellations, Milky Way, and bright green horizontal line.
The constellation Orion straddles the celestial equator, which is indicated by a green line on this chart. Since the celestial equator intersects horizons all over the world at points due east and due west (as shown on the chart above this one), the star Mintaka – the one directly on the green line – can be used to find those cardinal directions in your sky. Image via Aloha.net.

Mintaka shines on the celestial equator

Mintaka’s location on the celestial equator makes it a good guidepost for finding directions here on Earth. That is, Mintaka and the other stars of the Celestial Bridge are visible worldwide. From all over the world, Mintaka rises due east, sets due west, and remains in the sky for 12 hours. It climbs to its highest point in the sky midway between rising and setting.

When it’s highest in the sky, if this star shines at your zenith (your straight-overhead point), then you must be at the equator.

If this star shines in the southern half of your sky, then you must be north of the equator.

If this star shines in the northern half of your sky, then you must be south of the equator. From most of South America, for example, Mintaka appears in the northern sky.

The story of the Celestial Bridge is one of many about the constellation Orion. That’s because it’s so noticeable on our sky’s dome. Watch for it when you’re outside one evening soon!

Line drawing of sphere with circles around it and stick figure standing on it.
The celestial equator is an imaginary great circle on the dome of Earth’s sky, drawn directly above the equator of the Earth. Image via Physics.csbsju.edu.
Line drawing of hemisphere with slanted half-circle on it and stick figure in middle.
How you see the celestial equator in your sky depends on your latitude. But, because it’s above Earth’s equator, no matter where you are on the globe, the celestial equator intersects your horizon at points due east and due west. Image via Physics.csbsju.edu.

Bottom line: The indigenous Aymara people of the Andes and Altiplano regions of South America see the famous sky feature we know as Orion’s Belt as a celestial bridge between the sky’s Northern and Southern hemispheres. Its westernmost star, Mintaka, lies directly on the celestial equator.

Posted 
November 23, 2021
 in 
Tonight

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