12 Mysteries of the Sahara Desert: Facts That Will Surprise You

The Sahara is the largest hot desert on Earth, and one of the most mysterious places on the planet. It covers about 9 million square kilometres across North Africa, almost the size of the United States or China. Most people imagine endless sand dunes and burning heat, but the real Sahara is full of surprises: ancient lakes, giant stone “eyes”, snowfall, hidden water and even a connection to the Amazon rainforest.

Here are 12 of the most fascinating mysteries and facts about the Sahara Desert.

1. The Name Means “Desert Desert”

“Sahara” comes from the Arabic word ṣaḥrāʾ, which simply means “desert”. So when we say “the Sahara Desert”, we are really saying “the Desert Desert”.

2. The Sahara Was Once Green

This is the biggest mystery of all. Between roughly 11,000 and 5,000 years ago, the Sahara was covered in grasslands, trees and huge lakes. Scientists call this period the “Green Sahara” or African Humid Period. Hippos, crocodiles, giraffes and elephants lived where there is only sand today.

The change was caused by small, slow shifts in the Earth’s orbit, which moved the monsoon rains north. When the rains moved back south, the region dried out and became the desert we know.

3. Ancient Rock Art Shows a Lost World

In places like Tassili n’Ajjer in Algeria, thousands of rock paintings and carvings show people swimming, herding cattle and hunting animals that could never survive there today. These pictures are like photographs of the Green Sahara, made thousands of years ago.

4. The “Eye of the Sahara”

In Mauritania there is a giant circular formation about 40 kilometres wide, called the Richat Structure or “Eye of the Sahara”. It is so big that it is easiest to see from space. For a long time, people thought it might be a meteorite crater. Geologists now believe it is an eroded dome of rock layers, slowly worn down by wind and water into rings. Some online theories even link it to the legend of Atlantis, but there is no scientific evidence for that.

5. Most of the Sahara Is Not Sand

Surprisingly, sand dunes (called ergs) cover only about a quarter of the Sahara. Most of the desert is rocky plateaus (hamada), gravel plains (reg), dry valleys, salt flats and mountains.

6. It Has Mountains and Volcanoes

The Tibesti Mountains in Chad rise to about 3,400 metres at Emi Koussi, an old volcano. The Ahaggar (Hoggar) Mountains in Algeria are also dramatic volcanic landscapes.

7. It Can Snow in the Sahara

It sounds impossible, but snow has fallen several times near the town of Aïn Séfra in Algeria, on the northern edge of the desert. Photos of orange dunes covered in white snow went viral around the world.

8. Extreme Heat by Day, Cold by Night

Daytime temperatures in summer can go above 50°C. But because the air is so dry and there are few clouds, heat escapes quickly after sunset. Nights can become cold, sometimes close to freezing in winter.

9. Huge Amounts of Water Are Hidden Underground

Under the sand lies one of the largest groundwater reserves in the world, the Nubian Sandstone Aquifer, shared by Egypt, Libya, Sudan and Chad. Much of this “fossil water” fell as rain thousands of years ago during the Green Sahara period. Oases exist where this water reaches the surface.

10. Sahara Dust Feeds the Amazon Rainforest

Every year, strong winds lift millions of tonnes of Saharan dust and carry it across the Atlantic Ocean. Satellite studies show that some of this dust lands in the Amazon rainforest, bringing phosphorus, a nutrient that helps the rainforest’s soils stay fertile. The world’s largest desert helps feed the world’s largest rainforest.

11. Amazing Animals Survive There

• Fennec fox: the smallest fox in the world, with giant ears that release heat
• Dromedary camel: can go many days without water
• Saharan silver ant: one of the most heat-tolerant animals on Earth, it forages in the hottest part of the day
• Addax: a rare desert antelope that hardly ever needs to drink

12. People Have Lived There for Thousands of Years

The Sahara is not empty. Groups such as the Tuareg, known as the “blue people” because of their indigo clothing, have travelled its trade routes for centuries. Caravans once carried salt, gold and goods between North and West Africa, connecting great trading cities like Timbuktu.

Countries the Sahara Covers

The Sahara stretches across parts of about 11 countries and territories, including Algeria, Chad, Egypt, Libya, Mali, Mauritania, Morocco, Niger, Sudan, Tunisia and Western Sahara.

Will the Sahara Become Green Again?

Many scientists believe the Sahara has switched between green and dry many times over hundreds of thousands of years, following cycles in the Earth’s orbit. It will likely become green again one day, but not for thousands of years.

Frequently Asked Questions

Is the Sahara the largest desert in the world?

It is the largest hot desert. The largest deserts overall are Antarctica and the Arctic, because a desert is defined by very low rainfall, not by heat.

How big is the Sahara Desert?

About 9 million square kilometres, stretching roughly 4,800 km from the Atlantic Ocean to the Red Sea.

Why did the Sahara become a desert?

Slow changes in the Earth’s orbit shifted the monsoon rains south about 5,000 years ago, and the green landscape dried out.

Can you visit the Sahara?

Yes. Popular places to experience it include Merzouga in Morocco, Douz in Tunisia and the White Desert in Egypt. Always travel with a licensed local guide and check travel advice for safety.