One of the driest places on Earth !
The Atacama Desert is considered as one of the driest places on Earth. Covering an area of 181,300 square kilometers, the Atacama desert is enclosed to the East by the main chain of the Andes, while to the West lies a secondary mountain range of the Andes called Cordillera de Domeyko.
Extending from a few kilometers south of the Chile-Bolivia border to about 30° south latitude, it is made up of salt basins (salares), sand and lava flows, and is more than 20 million years old. The driest portion of this region is located south of the Loa River and west of the Cordillera Domeyko, near San Pedro de Atacama and Toconao, villages located at a very short distance of the ALMA Observatory.
Large volcanoes dominate the landscape, including the Licancabur, Acamarachi, Aguas Calientes and the Láscar. The latter is one of the most active volcanoes in Chile. All of them are located along the eastern side of the Salar de Atacama, forming a generally north-south trending line of volcanoes.
The cold Humboldt Current and the anticyclone of the Pacific are essential to keep the dry climate of Atacama Desert.
Some locations in the Atacama do receive a marine fog known locally as the Camanchaca, providing sufficient moisture for the development of a very specific and unusual flora .
Due to its otherworldly appearance, the Atacama has been used as a location for filming Mars scenes. In 2003, a team of researchers published a report in Science magazine titled "Mars-like Soils in the Atacama Desert, Chile, and the Dry Limit of Microbial Life" in which they duplicated the tests used by the Viking 1 and Viking 2 Mars landers to detect life, and were unable to detect any signs in Atacama Desert soil. The region may be unique on Earth in this regard.
Because of its dryness, its high altitude, nearly non-existent cloud cover, and lack of light pollution and radio interference from the very widely spaced cities, the desert is one of the best places in the world to conduct astronomical observations.
More information about the Atacama Desert on Wikipedia
Sunset at the moon valley, close to San Pedro de Atacama. In the background, the Licancabur volcano. Credit: ALMA (ESO/NAOJ/NRAO) V. Boué