Antarctica is the driest place on Earth. Parts of the continent have seen no rain for two million years. A desert is technically defined as a place that receives less than 10 inches of rain a year. The Sahara gets just 1 inch of rain a year.

As well as the driest place on Earth, Antarctica can also claim to be the wettest and the windiest. Seventy percent of the world’s fresh water is found there in the form of ice, and its wind speeds are the fastest ever recorded. The unique conditions in the Dry Valleys of Antarctica are caused by so-called katabatic winds. These occur when cold, dense air is pulled downhill simply by the force of gravity. Though Antarctica is a desert, these completely dry parts of it are called, somewhat ironically, oases. They are so similar to conditions on Mars that NASA used them to test the Viking mission.