The world's largest deserts: the Sahara, Antarctica and the Thar

The word "desert" usually brings to mind sand dunes, a blazing sun and a caravan of camels. But did you know that the world's largest desert is covered in ice? Here are the world's largest deserts, along with why India's Thar Desert is special in the world.

What is a desert?

A desert is defined not by heat but by a lack of rain. Usually an area that gets less than 250 millimetres of rain in a year is called a desert. Such areas can be hot, or extremely cold. Because of this definition, Antarctica and the Arctic, where very little snow or rain falls, are the largest deserts in the world. About a third of Earth's land is desert or dry land.

The largest deserts in the world

The Sahara is so big that almost the whole of the United States would fit inside it. Yet about 6,000 to 10,000 years ago the same Sahara was green, with lakes, grasslands and animals — ancient paintings on its rocks bear witness to this.

India's Thar Desert

The Thar, also called the "Great Indian Desert", covers about 200,000 square kilometres across India and Pakistan, and most of its Indian part lies in Rajasthan. It is counted among the most densely populated deserts in the world. The sand dunes of Sam near Jaisalmer, the forts of Jodhpur and Bikaner and a colourful folk culture are its hallmarks — read more about Rajasthan in Why Jaipur is called the Pink City. India's longest canal, the Indira Gandhi Canal, is bringing water to large parts of the Thar and making them fit for farming.

Did you know? India also has cold deserts — Ladakh and the Spiti valley of Himachal are high-altitude cold deserts with very little rain. And Gujarat's "Rann of Kutch" is a vast white desert of salt.

Some desert records

• The driest: the Atacama Desert in South America (Chile), where some places have had no recorded rain for decades.
• The hottest temperature: 56.7 °C was recorded in Death Valley, USA, in 1913, which the World Meteorological Organization accepts as the official record.
• The tallest dunes: in deserts such as the Sahara and the Namib, some sand dunes are hundreds of metres high.

The camel: the ship of the desert

The camel is called the "ship of the desert" because it can travel long distances over sand. Many people believe a camel stores water in its hump, but in fact the hump holds fat, which it uses for energy when food is scarce. A thirsty camel can drink more than 100 litres of water within minutes. Its long eyelashes and closable nostrils protect it from sand, and its broad feet keep it from sinking.

Spreading deserts: a warning

Because of tree-cutting, overgrazing and climate change, fertile land is slowly turning barren. This is called "desertification". To raise awareness of it, "Desertification and Drought Day" is observed every year on 17 June. Read more about our planet in Interesting facts about Earth.

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