Atacama Desert

The Atacama Desert is a coastal desert running roughly 1,600 kilometers down northern Chile, wedged between the Andes and the lower Chilean Coast Range, and is widely cited as the driest non-polar place on Earth. Its extreme aridity comes from a rain shadow cast by the Andes on its eastern side together with the cold, upwelling Humboldt Current offshore, which chills the air above the coast and suppresses the convection that would otherwise produce rain; some interior weather stations have never recorded measurable rainfall in the historical record. Despite this, the desert is not lifeless: fog banks rolling in from the Pacific, known locally as camanchaca, sustain isolated fog oases called lomas, where cacti, bromeliads and other specially adapted plants and the animals that depend on them survive on moisture condensing directly from the air rather than rain. The desert also holds striking landscapes such as the Valle de la Luna, ancient geoglyphs left by pre-Columbian peoples, and, because its air is so dry and its skies so consistently clear, some of the world's most powerful astronomical observatories, including the Atacama Large Millimeter Array. Its combination of extreme dryness, high-altitude ultraviolet exposure and Mars-like soil chemistry has also made it a working analogue site for astrobiologists studying the limits of life and testing instruments bound for Mars.