Human ignorance, sadly, isn't limited to planet Earth. Even today, over 400 years after the Age of Enlightenment began, plenty of people are still getting plenty of stuff wrong--not just about our home planet, but about the whole universe. Luckily, Jeopardy!s Ken Jennings is the author of a new book about the mysteries of the cosmos, the Junior Genius Guide to Outer Space. In this month's Debunker columns, he'll set us straight on a whole sky full of starry slip-ups. These are some misconceptions of truly astronomical proportion.
The Debunker: Star Myth #1: Is the Big Dipper a Constellation?
Ask someone to name a constellation in the night sky, and odds are most of them will first think of the Big Dipper, the seven bright stars that gleam overhead on summer nights in an unmistakable sickle-shaped pattern. The Big Dipper has helped humans navigate for millennia by pointing the way to Polaris, the North Star. Virtually every culture had its own name for the Dipper, from the "Drinking Gourd" of West Africa to the "Seven Gods" of Mongolia to the "Charles' Wagon" of the Vikings. It's iconic enough to have been borrowed for the corporate logo of Iridium Communications and on the state flag of Alaska. But the world's most famous constellation isn't actually a constellation at all. It's an asterism.
This isn't just pointless pedantry. In astronomy, a constellation is a particular region of the sky, not just an obvious pattern of stars that appears there. The 88 official constellations chosen by the International Astronomical Union in 1922 are mostly based on the groupings used in the ancient world, so they can each be identified with a little picture they're said to resemble. But Orion, technically speaking, isn't just the bright 'X' of four stars surrounding a "belt" that you're probably picturing. It's also every other star that can be found in that part of the night sky--and there are hundreds of them. (Eighty-one are bright enough to make the Bayer-Flamsteed list of prominent stars.)
Okay, you say. So the Big Dipper isn't just the bright ladle, it's also a bunch of other, dimmer stars scattered around the ladle. Got it. But that's not true either. The Big Dipper is just a group of stars, or "asterism," that makes up part of a much larger constellation: Ursa Major, or the Great Bear. As the bear is usually drawn, the dipper is just its hindquarters and tail. Other bright stars form its head, body, and legs. So the next time you spot the Big Dipper, try to take in the big picture. You're looking at a bear's butt.
Quick Quiz: What 7'1" athlete was nicknamed "the Big Dipper," as he often had to dip his head to walk through doorways?
Ken Jennings is the author of six books, most recently his Junior Genius Guides, Because I Said So!, and Maphead. He's also the proud owner of an underwhelming Bag o' Crap. Follow him at ken-jennings.com or on Twitter as @KenJennings.