Where is the largest desert?

Contrary to popular belief, the largest desert on Earth is Antarctica, covering 14.2 million square kilometers. A desert is defined by low precipitation (under 250 mm/year), and Antarctica's interior receives only about 51 mm annually — making it drier than the Sahara. The Arctic is the second largest desert at 13.9 million sq km. The Sahara in North Africa is the largest hot desert at 9.2 million sq km (roughly the size of the United States). The Sahara's temperature can swing from 50°C during the day to below freezing at night. Interestingly, about 6,000 years ago the Sahara was a lush green landscape with lakes, rivers, and abundant wildlife — a period known as the "Green Sahara" or African Humid Period.