Some parts of the Atacama Desert in Chile have not seen a single drop of rain for over 400 years.

The Atacama Desert is a 1,000-kilometer strip of land in South America. It is the driest place on Earth outside of the North and South Poles. Some weather stations in the desert have never recorded any rain since they were built. The average rainfall for the whole region is only 1 millimeter per year.The Andes Mountains block moist air coming from the east. The Chilean Coast Range blocks wet air coming from the west. A cold ocean current called the Humboldt Current also stops rain clouds from forming over the coast. These three factors combined prevent almost all precipitation.The soil in the driest parts of the desert is similar to the soil on Mars. NASA uses this area to test robots and tools before sending them to space. The ground is so dry that it preserves ancient items. Scientists found mummies there that are over 7,000 years old and have not rotted.Even without rain, some tiny organisms survive by drinking water from thick coastal fog. This fog is called camanchaca. The air is also very clear because there is no water vapor in it. This makes the desert the best place on Earth for giant telescopes to look at stars.