Atacama: The Driest Place on Earth

You're looking at a desert so extreme that some areas haven't recorded a single raindrop in all of human history. Stretching roughly 1,600 kilometers through northern Chile, the Atacama is officially the driest non-polar desert on Earth — about fifty times drier than Death Valley. It hosts ancient mummies, world-class telescopes, and microbes surviving at the absolute edge of life. There's far more to this place than just sand and silence.

Key Takeaways

• The Atacama Desert is Earth's driest non-polar desert, with some regions receiving measurable rainfall as seldom as once every 20 years.
• Parts of the Atacama recorded no significant rainfall for roughly four centuries, from 1570 to 1971.
• Despite extreme aridity, over 550 plant species survive here, with more than 60% found nowhere else on Earth.
• The cold Humboldt Current creates coastal fog through temperature inversion, producing no rain but sustaining specialized desert life.
• Microbes survive by activating metabolically only when rare moisture arrives, then shutting down completely during prolonged dry periods.

What Makes the Atacama the Driest Place on Earth?

The Atacama Desert isn't just dry—it's the driest non-polar desert on Earth, and several powerful forces work together to keep it that way.

The Andes Mountains block moisture from the Amazon Basin, while the coastal Cordillera creates a double rain shadow that prevents humid air from reaching inland. The cold Humboldt Current cools the air above the Pacific, reducing its moisture capacity and pushing dry winds toward the desert. Subtropical high-pressure systems suppress cloud formation by forcing air downward, eliminating any chance of rainfall. A persistent temperature inversion traps cool ocean air beneath warmer land air, producing oceanic fog but zero precipitation. Over time, these conditions have baked the landscape into cracked salt flats and ancient, bone-dry soil. In fact, some areas receive no measurable rainfall for years at a stretch, making certain stations among the most precipitation-deprived recording sites on the planet.

Scientists estimate the Atacama is between 10 and 15 million years old, making it the oldest desert on Earth and a landscape shaped by extreme aridity over an almost incomprehensible span of time. By comparison, the Namib Desert of Southern Africa has existed for at least 55 million years, suggesting that while the Atacama holds the title for driest, other ancient deserts rival it in sheer geological age.

Just How Little Rain Does the Atacama Actually Get?

When most people picture a desert, they imagine occasional dry spells broken by sudden downpours—but the Atacama shatters that expectation entirely.

The extreme dryness here defies easy comprehension. Arica, Chile, averages just 0.03 inches per year, while coastal hyperarid zones record between 0 and 5 mm annually. Some areas, like Yungay's surroundings, have received zero rainfall throughout recorded human history.

Rainfall variability across the region is striking. High-Andean zones get under 80 mm yearly, while the overall desert averages roughly 3 inches, falling mostly between December and March. Certain spots measure less than 1 mm annually. While the Atacama holds the title of driest non-polar desert, the McMurdo Dry Valleys of Antarctica have gone an estimated 2 million years without rain or snow, making them the driest place on Earth overall.

When rain does arrive—like the 2015 event delivering 1–2 inches in 24 hours—it represents years' worth of precipitation, triggering deadly mudflows and floods in communities completely unprepared for moisture. The Copiapó River, virtually dry for 17 years before the 2015 storm, rapidly filled and overflowed its banks, illustrating how even a single rainfall event can overwhelm a landscape unaccustomed to water.

Historical records suggest that parts of the Atacama may have gone without significant rainfall for the entire stretch between 1570 and 1971, a span of four centuries, underscoring just how profoundly and persistently arid this desert can be.

Where Exactly Is the Atacama Desert Located?

Stretching along the Pacific coast of South America, the Atacama Desert sits primarily in northern Chile, centered around 24°30′S 69°15′W and running roughly 1,600 km from near Arica in the north down to near La Serena in the south.

You'll find it wedged between the Andes Mountains to the east and the Pacific coastal margins to the west, covering approximately 105,000 km².

The desert includes the Region of Antofagasta, where San Pedro de Atacama serves as a central hub.

Massive salt pans define much of the terrain, including the Salar de Atacama, a 1,000-square-mile salt basin sitting at 7,500 feet.

North of 19°30′S, drainage flows toward the Pacific, while south of that line, endorheic basins trap water internally.

The desert also extends into southwestern Bolivia and borders Peru to the north. The Cordillera de la Costa forms the desert's western boundary, while the Cordillera Domeyko defines its eastern edge along the Andean foothills.

The region's extreme aridity is largely the result of a rain shadow effect, created by the Andes blocking moisture from the east while the coastal range limits humidity from the Pacific.

Chile's extraordinary length of over 4,200 kilometers north to south means the Atacama represents just one extreme of the country's remarkably diverse range of climates, which also includes Mediterranean conditions in the center and glaciers in the far south.

Why Is the Atacama So Impossibly Dry?

Now that you know where the Atacama sits, you might wonder what makes it so brutally dry. Four powerful forces work together to strip the region of almost all moisture.

First, the andes rainshadow effect blocks Atlantic moisture entirely. Moist Amazon air rises over the Andes, dumps its rain on the eastern slopes, and delivers only parched air westward. A secondary barrier, the Chilean Coast Range, doubles this effect.

Second, the cold Humboldt Current creates a coastal inversion, cooling the air above the Pacific and preventing clouds from producing rain. You'll see fog and stratus clouds, but no actual precipitation reaches the ground.

Finally, descending katabatic winds and a persistent subtropical high-pressure system push air downward, suppressing cloud formation and locking in extreme aridity year-round. The Walker circulation also influences how clouds move through the region, further reducing any chance of meaningful rainfall. Despite this relentless dryness, temperatures remain surprisingly moderate, with average summer temperatures in coastal areas like Antofagasta reaching only around 65°F (18°C). The combined absence of rain and high evaporation rates push the desert to extremes that make it roughly fifty times drier than Death Valley.

What Actually Lives in the Atacama: and How It Survives?

Despite near-total aridity, the Atacama teems with life — you just have to know where to look. Microbial resilience defines survival here, with bacteria activating metabolically only when episodic moisture arrives, then shutting down completely during dry periods. Scientists studying these microbes now use a method that separates DNA from living cells and dead cells, revealing living microbial communities that traditional DNA analysis alone would miss.

Here's what's actually thriving beneath your feet:

1. Bacteria produce biofilms, pigments, and antibiotics to survive UV radiation and nutrient scarcity.
2. Nematode diversity spans 21 families and 36 genera, with richer communities appearing wherever humidity increases.
3. Darwin's leaf-eared mouse extracts water directly from seeds and fruits, requiring no standing water to survive.

Even scorpions, lizards, and small songbirds carve out niches here, proving the Atacama's harshness doesn't equal lifelessness. The region's plant life is similarly tenacious, with roughly 550 species of ferns, gymnosperms, and flowering plants recorded across the ecoregion, more than 60% of which exist nowhere else on Earth.

The Atacameños: Thousands of Years of Desert Survival

While microbes and mice have mastered the Atacama's extremes, humans have called it home for over 10,000 years. The Atacameños built their survival around oasis agriculture, cultivating maize, quinoa, and potatoes using ancestral irrigation systems that channeled mountain runoff and tapped underground water sources.

They weren't isolated. These communities thrived through textile trade, exchanging goods with Andean highland and coastal societies across vast desert networks. Their distinct ceramic styles reflected cultural sophistication, evolving through Tiwanaku influence and beyond.

Spanish colonization shattered much of that legacy, displacing traditions and imposing Christianity. The War of the Pacific then folded them into Chilean nationality. Today, Atacameño communities persist in San Pedro de Atacama and surrounding oases, actively reclaiming their language, heritage, and unresolved land rights. Across the desert landscape, petroglyphs and ceremonial sites endure as physical markers of their spiritual relationship with the sun, mountains, and water sources they once venerated.

Atacameño social life has long been structured around ayllus, communities bound by shared ancestral roots, collective decision-making, and mutual aid that sustained cohesion across generations of hardship.

Mummies, Parrots, and the Ancient Secrets Buried in the Atacama

The Atacama's dryness doesn't just kill—it preserves. The Chinchorro mummies, dating back to 5050 BC, predate Egyptian mummies by 2,000 years. Ancient Chinchorro people developed sophisticated techniques to honor their dead, driven partly by arsenic-poisoned water causing high mortality rates.

Here's what makes these mummies remarkable:

1. Oldest artificial mummies ever found — discovered first in 1917, with 282 recovered since.
2. Advanced preservation methods — bodies were disassembled, stuffed with seaweed, reeds, and clay, then painted with black or red pigments.
3. Ritual significance — mummies traveled with living groups, reflecting deep ancestor worship.

Parrot symbolism also wove through Atacama cultures, representing spiritual connection and trade networks linking coastal and inland communities across this ancient desert landscape. Scholars continue to debate whether the Chinchorro developed mummification independently due to local environmental factors or inherited basic techniques from migrants originating in the Amazon River Basin. Remarkably, mummification was practiced across all social classes, with children and infants often receiving the most elaborate treatments of any group.

The Minerals That Made the Atacama Worth Fighting Over

Beneath the same sands that swallowed and preserved ancient Chinchorro bodies lies a different kind of treasure—one that didn't just shape cultures but sparked wars.

The Atacama holds massive deposits of copper, gold, silver, lithium, sodium nitrate, and iodine—resources so valuable they triggered 19th-century resource conflicts that literally redrew South American borders. Chile and Bolivia fought the War of the Pacific over access to these mineral-rich territories.

Sodium nitrate alone yielded nearly 3 million metric tons during World War I.

Today, iodine extraction operations run by companies like Soquimich continue alongside large-scale lithium mining that supplies roughly 40% of global reserves.

The desert that looks utterly barren actually sits atop some of the most strategically important mineral wealth on Earth. The Atacama is also characterized by a great abundance of saline minerals, formed through evaporation in closed basins that precipitates gypsum, salts, and borates across the region.

Mining has come at a significant environmental cost, as lithium extraction requires pumping surface and groundwater away, draining aquifers and lagoons that are already stressed by the region's extreme aridity and diminishing rainfall.

Why NASA Chose the Atacama to Simulate Mars

NASA didn't pick the Atacama by accident—it's the closest thing to Mars you'll find on Earth. Its extreme dryness, high UV radiation, and Mars-like geology make it one of the best planetary analogs available for testing life-detection technology.

Here's why it works so well:

1. Hyper-arid soils push instruments to detect biosignatures at the edge of what's measurable.
2. UV radiation levels—the highest on Earth—test sterilization protocols and microbial survival limits.
3. Salt flats and volcanic terrain replicate Martian geology for realistic rover navigation trials.

NASA's ARADS project deploys the K-REX2 rover here, drilling up to two meters deep through salt and rock, refining the exact technologies you'll see operating on Mars. The project is led by NASA's Ames Research Center, bringing together expertise in astrobiology and robotics to advance life-detection methods. Some regions of the Atacama receive rain as seldom as once every 20 years, making its aridity a near-perfect match for Martian surface conditions.

Why the Atacama Offers the World's Clearest Night Skies

Few places on Earth rival the Atacama Desert when it comes to stargazing, and that's no accident. The desert receives less than 0.04 inches of rain annually, stripping the atmosphere of moisture and maximizing atmospheric transparency.

Sitting above 2,400 meters, you're already above a significant portion of turbulent air, which sharpens every image overhead.

With over 300 clear nights per year and virtually no light pollution, conditions for celestial photometry are nearly perfect. You can see the Milky Way's dust lanes with your naked eye, spot faint nebulae on moonless nights, and watch planets align across the summer sky.

From the Catarpe Valley, away from San Pedro de Atacama's lights, the darkness rivals even Mauna Kea and La Palma. The Andes Mountains form a rain shadow that blocks moisture carried from the Amazon Basin, keeping skies consistently dry and transparent night after night.

The Chajnantor Plateau is home to ALMA's 66 radio telescopes, one of the world's most advanced observatory complexes, which takes full advantage of the desert's extraordinary atmospheric conditions.