Sahara

Desert World Wonders, World

The Sahara is among the largest deserts in the world, namely the largest hot desert on Earth, with an area of 9,000,000 km². Crossed by the Tropic of Cancer (23° 27′ N latitude), it is located in northern Africa, between 16° W longitude and 35° E longitude.

For several hundred thousand years, the Sahara has alternated between desert and savanna grassland in a 41,000 year cycle caused by changes ("precession") in the Earth's axis as it rotates around the sun, which change the location of the North African Monsoon. It is next expected to become green in about 15,000 years (17,000 AD). There is a suggestion that the last time that the Sahara was converted from savanna to desert it was partially due to overgrazing by the cattle of the local population.