Atacama Desert

The Atacama Desert (Spanish: Desierto de Atacama [ataˈkama]) is a desert plateau on the Pacific coast of South America, stretching along a 1,600-kilometre-long (1,000-mile) strip of land in northern Chile, west of the Andes. It covers an area of 105,000 km2 (41,000 mi2), rising to 128,000 km2 (49,000 mi2) if the barren lower slopes of the Andes are included. The Atacama is the driest non-polar desert in the world and the largest fog desert on Earth. Extreme aridity results from its position between two mountain chains—the Andes and the Chilean Coast Range—of sufficient height to block moisture from both the Pacific and Atlantic oceans, creating a two-sided rain shadow. The cool, north-flowing Humboldt Current and the South Pacific anticyclone reinforce this effect. Average annual rainfall is around 15 mm (0.6 in) per year, and some weather stations in the desert have never recorded rain. Evidence suggests the desert may have received no significant rainfall from 1570 to 1971, and hyper-arid conditions date back at least to the Miocene. As of September 2026, there are new doubts regarding the continuity of Atacama desert's hyperaridity, following a publication by Gutstein et al. regarding semiaquatic fossil finds in northern Chile, dated 8.8 Ma. The desert borders Peru to the north and the Chilean Matorral ecoregion to the south, with the less arid Central Andean dry puna to the east. Its high altitude, dry air, and near-total absence of light pollution make it one of the world's premier sites for astronomical observation, hosting several major observatories including the Atacama Large Millimeter Array (ALMA) and the Very Large Telescope. Its soil composition and near-total absence of microbial life have also made it a testing ground for Mars mission instruments. The desert has been inhabited since at least 7000 BCE, when the Chinchorro culture settled along...