Atacama Desert (María Elena South)

The Atacama Desert is a high, dry plateau on the Pacific coast of South America, in northern Chile, west of the Andes. It stretches along a strip about 1,600 kilometres long and covers roughly 105,000 square kilometres. It is the driest non-polar desert in the world.

Two mountain chains, the Andes and the Chilean Coast Range, block moisture from both oceans. The cold Humboldt Current adds to the dryness. The average rainfall is only about 15 millimetres a year, and some weather stations have never recorded any. Its clear, dark sky makes it one of the best places on Earth for telescopes.

Why it is so dry

The desert sits in a double rain shadow: mountains on both sides stop clouds from reaching it. The cold, north-flowing Humboldt Current and a high-pressure system over the South Pacific keep the air stable and rainless.

Evidence suggests there may have been no major rainfall from 1570 until 1971 in places, and very dry conditions go back at least millions of years.

People, stars and Mars

People have lived here since at least 7000 BCE, when the Chinchorro culture settled along the coast. In the 19th century, sodium nitrate deposits made the region a battleground in the War of the Pacific among Chile, Bolivia and Peru.

Today the dry, clear air hosts observatories such as ALMA and the Very Large Telescope. Its soil, almost free of microbes, is also used as a test site for Mars mission instruments.

On the globe

The model shows the pale, barren desert plateau of northern Chile, with dry ground and sparse features.