If you’ve been kind enough to have read my column for some time, you know how much I love the constellation Orion the Hunter. It’s the absolute king of the winter skies and one of my best non-human friends. I look for Orion as soon as I head outside on clear winter nights. I know I’m not the only Orion lover. Like the Big Dipper, Orion is one of the most recognizable constellations in the night sky. Except that the Big Dipper isn’t actually one of the 88 official constellations seen from Earth. The Big Dipper is an asterism, or a pattern of stars, that makes up the rear end and tail of the constellation Ursa Major, the Big Bear. So, Orion is the most recognizable constellation as far as I’m concerned. Its calling card is the three stars neatly lined up in a row that make up the celestial hunter’s belt. There’s no other line of stars as bright anywhere else in the celestial dome.
Over the years, cultures worldwide have come up with nicknames for Orion’s belt that have nothing to do with a mighty hermit hunter. It’s been called the staff of St. Peter, one of the Apostles. The stars have also been called the Three Kings that visited the Christ child shortly after he was born in Bethlehem. That makes sense because Orion’s belt starts showing up in the evening night sky in December. Orion’s trio of stars also appears in the Bible in the Book of Job, “Canst thou bind the sweet influences of the Pleiades, or loose the bands of Orion?” (King James Version).
I’ve also heard Orion’s belt referred to as the Three Amigos, the Three Musketeers, and the three blind mice. I’ve even referred to them as the Three Stooges. Some years ago in Waconia, Minn., at one of my Minnesota Starwatch programs, a woman told me that on the farm she was raised on, they referred to the stars as Wynken, Blynken and Nod, characters in a popular old American children’s poem.
This time of year, Orion and his famous belt of stars proudly shine almost directly above the southern horizon as evening twilights end. From the lower left to the upper right, the belt stars are named Alnitak, Alnilam and Mintaka. You would think these stars are physically related to each other, but that’s not the case, not even close. They have nothing to do with each other astronomically. They’re hundreds of light-years apart. Their arrangement in our sky from our vantage on planet Earth is purely accidental. Or is it?
All three stars are much larger than our sun and are unique in their own ways. The largest of the trio is Alnilam, an Arabic name that roughly translates to English as “string of pearls.” That certainly seems appropriate. Alnilam is about 26 million miles in diameter, 30 times the diameter of our sun! At 1,976 light-years away, Alnilam is so far that even if you could travel at the speed of light, 186,300 miles a second, it would take you nearly two millennia to get there, with or without your luggage. Alnilam is a scorching star with temperatures over 45,000 degrees. Our sun, by comparison, is 10,000 degrees at its outer layer. What amazes me is that Alnilam kicks out more than 100,000 times as much light as our sun. It’s a big shiner, for sure. If it were 19 light years away instead of 1,976 light years, it would easily be the brightest star in our sky. You’d even see Alnilam brightly in broad daylight.
Alnitak, on the lower left side of Orion’s belt, is an Arabic name that means “the belt”; it’s the second-largest of the three stars. This giant nuclear fusion-powered gas ball is over 21 million miles in diameter. Its surface temperature exceeds 60,000 degrees. Traveling to Alnitak would require a journey of more than 800 light-years. By the way, just one light year equals almost 6 trillion miles. Alnitak’s luminosity is 100,000 times that of our puny sun. There’s also more than meets the eye when you see Alnitak. It’s actually part of its own little three-star family. Alnitak has two smaller companion stars, and all three orbit each other. You cannot see Alnitak’s companion stars with the naked eye. Multiple star systems are common in our night sky. Many stars that appear as a single star may be part of a multi-star family, with the stars orbiting each other. If you were on a planet around one of these stars, you would have multiple suns in your sky.
Mintaka, on the upper right-hand side of the belt, is about the same size as Alnitak, and it has a surface temperature of over 50,000 degrees and is about 900 light years away. Just like Alnitak, Mintaka is another multiple-star system of at least two stars orbiting and eclipsing each other. As the two stars pass in front of each other, their combined brightness we see varies slightly over time.
Well, that’s it, the three stars that form Orion’s belt, one of the true jewels of the sky. The stars are different in size, power output, temperature, and more, yet they line up so neatly with nearly equal brightness from our view on Earth. I can’t help but think that maybe these three stars aren’t aligned just by chance but by a divine hand.
Mike Lynch is an amateur astronomer and retired broadcast meteorologist for WCCO Radio in Minneapolis/St. Paul. He is the author of “Stars: a Month by Month Tour of the Constellations,” published by Adventure Publications and available at bookstores and adventurepublications.net. Mike is available for private star parties. You can contact him at mikewlynch@comcast.net.
