As people around the world take shelter in place, many look forward to the day when they can travel again. To help people cope and remind them of how beautiful the world can be, BBC Travel updates some of our most popular stories about natural phenomena and man-made wonders.

Located along the Atlantic coast of southwest Africa, the Namib Desert is one of the driest places on the planet. Meaning “an area where there is nothing” in the local Nama language, this Martian-style landscape of towering sand dunes, craggy mountains and gravel plains spans some 81,000 km² across three country.

Dating back at least 55 million years, the Namib is considered the oldest desert in the world (the Sahara is believed to be only two to seven million years old). With summer temperatures regularly reaching 45 ° C and nights dropping below freezing, it is also one of the most inhospitable places on the planet. Yet, over time, a staggering number of species have adapted to inhabit this barren wonder – and in so doing, have created a bizarre geomorphic phenomenon that continues to baffle experts.

The Namib Desert stretches over 2,000 km from southern Angola to Namibia and northern South Africa. From where it falls dramatically into the ocean, this seemingly endless sea of ​​silica stretches east from Namibia’s Atlantic coast, reaching up to 160 km inland to the edge of the Great Escarpment of Southern Africa.

The more arid parts of the Namib receive on average only 2mm of precipitation per year. For a few years, parts of the desert receive none. But as if emerging from a mirage, animals like the oryx, springbok, cheetahs, hyenas, ostriches and zebras that have adapted to survive in these harsh conditions roam the desert.

Ostriches raise their body temperature to reduce their water loss; Hartmann’s mountain zebras are skillful climbers who have adapted to rugged desert terrain; and oryx can survive for weeks without drinking by eating foods rich in water like roots and tubers.

One of the most dangerous areas of the inhospitable Namib is a 500 km stretch of sand dunes and rusty ship hulls along the Atlantic, known as the Skeleton Coast. Stretching from southern Angola to central Namibia, the region takes its name from the many whale carcasses scattered along its shores and the nearly 1,000 wrecks that have littered its coastline over the centuries.

The austere Skeleton Coast is often shrouded in dense mists, created by the upwelling of the cold Benguela Current from the Atlantic Ocean, which collides with warm air from the interior of the Namib Desert. These mists create dangerous sailing conditions for ships, and the local San people have called the area “the land which God created in anger.”

While sailing along the west coast of Africa, the famous Portuguese explorer Diogo Cão briefly stopped on the Skeleton Coast in 1486. ​​After Cão and his men erected a cross bearing the Portuguese coat of arms Namib, the dreaded sand dunes and harsh climate soon led them back to the sea – but not before calling the region “Gates to Hell”.

Today, tourists come to Namib to see the spectacular ocher sand dunes that surround Sossusvlei, a salt and clay basin in the center of Namib-Naukluft National Park – Africa’s third largest national park, with nearly 50,000 km².

While sand dunes are a ubiquitous feature throughout Namib, the surrounding Sossusvlei has a particularly deep orange hue. This color is actually rust and is an indication of the oxidation process resulting from a high concentration of iron in the sands. The dunes in this region are also among the highest in the world. Many are over 200m tall, while the so-called “Dune 7”, located north of the red landscape of Sossusvlei, rises almost 400m into the sky.

Among the many wonders of the Namib, one of its most intriguing features and greatest mysteries is a geomorphic phenomenon known as ‘fairy circles’. Sometimes referred to as “fairy rings,” these barren patches of sand surrounded by a single species of grass are found throughout the Namib Desert and have baffled experts for decades.

The rings are best viewed from the sky, where one can marvel at the matrix of circles that stretches endlessly across the desert sands. Found both in the flat gravel plains of the Namib and on the desert dunes, the fairy rings retain their almost perfectly circular shape on both terrains. The circles measure between 1.5m and 6m in diameter in central Namib, while in northwest Namibia they are about four times the size and can grow up to 25m wide.

For years, it was thought that fairy rings only existed in Namibia, but in 2014, similar formations were discovered in Western Australia when environmental scientist Bronwyn Bell studied the remote region of Pilbara. Puzzled by these spectacular formations, she contacted Stephan Getzin, an environmentalist and fairy circles specialist based in Germany, to share her discovery. While Australian circles closely resemble those found in Namibia, the differences in their soil makeup have baffled scientists even more.

While experts are mystified by the cause of these “fairy” formations, the circles have long been known to local Namibians. The local Himba people believe that they are caused by spirits and are footprints left by their god, Mukuru.

To understand their origin, mathematicians even tried to create patterns to see if the rings match a recognizable pattern. But Hein Schultz, the owner of the Rostock Ritz Desert Lodge located just outside the Namib-Naukluft National Park, says some locals believe these mysterious circles are caused by “UFOs or fairies dancing at night.”

To this day, there remains no universally accepted theory as to the source of these curious circles. But in recent years, scientists from Namibia, Germany, the United States and elsewhere have gathered to study the phenomenon in the hopes of better understanding it.

At the Gobabeb РNamib Research Institute, a remote research center in the heart of the desert, entomologist Eug̬ne Marais explained that the two big theories stem from the scarcity of water in Namib. Some research suggests that circles are caused by termites, which create these circles in order to harvest water and nutrients from the soil. By clearing vegetation from the soil, termites create a sterile space in the soil, which allows precipitation to seep deeper into the soil. The theory suggests that termites stay hydrated by drinking from these underground reservoirs year round.

The other big theory is that of “the self-organization of vegetation”, where root competition between grasses makes the bare circular patches appear as a reservoir from which to extract nutrients and water from the surrounding area.

After years of drought, the grass in fairy circles can eventually wither and appear to disappear. Marais highlights the wonder of this landscape by saying that when it rains, all of a sudden, “as if by magic”, the circles reappear.

According to Marais, research on the Namib fairy rings has generally focused on circles in isolated expanses of desert gravel plains or those found in sand dunes. But to really understand these formations, he believes that research must extend to both fields.

Ultimately, Marais has a hunch that these strange spots that dot the desert are caused by a combination of factors. But what exactly these factors are remains a mystery to this day.

World of wonders is a BBC Travel series exploring some of the most awe-inspiring natural phenomena and man-made wonders from around the world.