Every Tuesday, we ask Jeopardy! know-it-all Ken Jennings to blow our minds by debunking a cherished myth that “everybody knows” — even though it’s dead wrong. Since Ken’s new book Maphead, about geography nerds, is in stores now, we pulled him away from the gazetteer long enough for him to demolish four incredibly wrong “facts” about geography.
Map Myth #4: The Sahara Is the World’s Largest Desert.
I know you want to appeal to a map here, Sahara-defenders. Look at its huge beigeness! It’s like, half of Africa, the second-biggest continent! “Saharan” is actually a dictionary word meaning “vast, desert-like.” How could it not be the biggest?
But here’s the rub: a geographer’s definition of “desert” has nothing to do with temperature, or sandstorms, or cacti, or dudes on camels, or any of that stuff. If you want to be a desert, all you have to do is not rain. The general rule of thumb: if less than ten inches of precipitation falls somewhere in a year, then it’s a desert. And the Earth’s driest continent gets much less than that — only eight inches annually at its wettest spots, along the coast. Yes, the world’s biggest desert is actually chilly Antarctica. Much of the Antarctic interior gets only a couple inches of snow a year, and cold air carries so little moisture that the relative humidity can be as low as 1% . If you’re going to the South Pole, bring Chapstick.
So what’s the Sahara then — the world’s largest sandy desert? Nope, that’s another misconception. Most of the Sahara is a rocky plateau, not a sea of dunes. (The Arabian Desert is the world’s largest sandy desert.) The Sahara is usually called the world’s largest hot desert. I know it must hurt the locals to have to agree to this asterisk, but what can they do? Antarctica is two million square miles bigger than their puny runner-up desert. It beats the Sahara cold.
Quick Quiz: What fictional alien planet is named for the southernmost province of the Saharan nation of Tunisia?
Ken Jennings is the author of Brainiac, Ken Jennings's Trivia Almanac, and the new Maphead. Follow him at ken-jennings.com or on Twitter as @KenJennings.
Photo by Flickr member http2007, used under a Creative Commons License.