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What is the Largest Desert on Earth?

Satellite-derived image of the surface topography of Antarctica. Image Credit: Jonathan Bamber
A desert is a region of the Earth that receives little or no precipitation; either rain or snow. They’re often some of the hottest, most inhospitable places on Earth, Death Valley in the US. But deserts can be cold too, like in the Arctic and Antarctica. Altogether, deserts make up one-third of the surface of the Earth. But what is the largest desert on Earth?

You might be surprised to know that the largest desert on Earth is the Antarctic Desert, with a total size of 13.8 million square kilometers. The second largest desert is the Arctic, with 13.7 million square km. The third largest desert in the world is the more familiar Sahara, with a total size of 9.1 million square km.

Antarctica is the coldest, windiest, and most isolated continent on Earth. It’s covered by a permanent ice sheet that contains 90% of the Earth’s fresh water. The 2% of the continent that isn’t covered by ice is along the coasts, and that’s where all the life is. Rainfall (or snowfall) in this region of Antarctica is less than 20 millimeters/year.

But when you think of a desert, you’re thinking of a hot place. So the largest hot desert is the Sahara in northern Africa. At 9.1 million km2, it’s as large as the United States or the continent of Europe. Scientists believe the region has been a desert for as long as 3 million years. On average, the Sahara receives less than 8 cm/year of rainfall, and temperatures can rise to more than 50 degrees C.

We have written many articles about the Earth for Universe Today. Here’s an article about how deserts can teach researchers about how to search for life on Mars. Here’s an article about the biggest continent.

Want more resources on the Earth? Here’s a link to NASA’s Human Spaceflight page, and here’s NASA’s Visible Earth.

We have also recorded an episode of Astronomy Cast about Earth, as part of our tour through the Solar System – Episode 51: Earth.

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