When you hear the word “desert” you probably think of camels and sand dunes. But scientists define a desert as anywhere that gets less than 25 centimetres of precipitation per year. Antarctica gets less than 5 - making it, at 14 million square kilometres, the largest desert in the world.
Almost all of that precipitation falls as snow, which doesn’t melt and instead piles up over thousands of years into thick ice sheets. About 90 percent of all the ice on Earth is locked up in Antarctica.
The strangest places are the McMurdo Dry Valleys. The wind there is so fierce and dry that snow evaporates straight into the air without ever melting. Some of those valleys haven’t had liquid water for around two million years - about as close to Mars as you can get without leaving Earth.
