Thousands of "fairy circles" stretch out across the Namib Desert. But what's behind the vast polka-dot pattern? Scientists are at odds.
Image: picture alliance/WILDLIFE/T.Dressler
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Humans have long sought ways to explain why certain planetary events occur, whether those are geological, heavenly, environmental or weather-related. But in the absence of science, humans have often turned to storytelling.
Some ancient cultures believed the temporary extinguishment of the sun during a total eclipse was the result of some evil being trying to gobble it up. Earthquakes, volcanoes and tsunamis have been put down to the wrath of gods.
Over the years, we have found scientific explanations for many of these phenomena but scientists don't always find agreement, as is the case with the "fairy circles" of Namibia. The circles are actually patches of bare soil surrounded by vegetation. They appear in their thousands in the Namib Desert.
Fairy circles are patches of bare soil in grasslands that form a uniform circular patternImage: picture-alliance/dpa/Stephan Getzin
The fairy circles have largely defied explanation. According to local legend, they are footprints left by the gods or burnt patches caused by a dragon's fiery breath. Scientists have come up with theories that include the circles being formed by ostriches rolling around in the dust as well as contamination by radioactive materials.
Plants or termites?
There are, however, two leading explanations for the formation of the circles — both of which have passionate adherents. One hypothesis suggests the circular patches are caused by underground sand termites that have cleared vegetation in the areas around their nests. The other claims plants competing for water can explain the pattern.
Both camps fiercely defend the rigors of their respective hypotheses, but earlier this year a team of scientists published findings in the journal Nature suggesting both hypotheses were right. The appearance of the circles "cannot be explained by either mechanism in isolation." The team's computer models found the pattern could be best explained as an interplay between the termites and plants.
Still, not everyone is happy with this suggestion. Dr Stephan Getzin from the Helmholtz Centre for Environmental Research in Germany, who is firmly on team plant, said at the time, that the research didn't address the presence of such circles in areas with no termites.
It seems, the mystery has not quite been solved.
Nature's extremes
From the bone-dry Atacama Desert to a really rainy village in India, from the highest peaks to the darkest depths - our Earth is an amazing place. Check out some of nature's most extreme spots!
Image: AP
Coldest place on Earth: East Antarctic Plateau
It's more than a little chilly on this high ridge in Antarctica. On a cold winter's night, temperatures plummet as deep as -92 degrees Celsius (-133.6 degrees Fahrenheit). This could change in the future though: US scientists have just measured the highest monthly global CO2 concentration since the beginning of modern records. Greenhouse gas is a chief contributor to global warming.
Image: EPA/YONHAP NEWS AGENCY
Hottest place on Earth: Death Valley, United States
The sweltering heat reached in the Death Valley National Park in the US state of California is far too hot even for avid sun worshipers. The highest-ever temperature recorded here at Greenland Ranch was 56.67 degrees Celsius (134 degrees Fahrenheit) on July 10, 1913. That's more like stepping into a furnace than enjoying a warm summer day.
Image: gemeinfrei
Highest place on Earth: Mount Everest, Nepal
The world's highest peak is the summit of Mt. Everest in the Himalaya mountain range, at 8,848 meters (29,029 feet). The first people to climb it were Edmund Hillary from New Zealand and Nepali Sherpa climber Tenzing Norgay on May 29, 1953. The earthquake that devastated Nepal on April 25, 2015, also sent avalanches down Mt. Everest, killing at least 18 people and ending the climbing season.
Image: Getty Images/P. Bronstein
Earth's lowest point: Challenger Deep, Pacific
You'll have to enter a submarine to reach Earth's lowest spot: Challenger Deep lies in the Mariana trench in the western Pacific Ocean, north of Guam. Only three people have ever been that deep underwater - one of them was filmmaker James Cameron, who took a submarine down the 11-kilometer-long (6.8-mile) undersea valley in 2012.
Image: REUTERS
The driest spot on Earth: Atacama Desert, Chile
If you ever get sick of constant drizzle in your hometown, the Chilean Atacama Desert is the place to go. At its heart, a place climatologists call absolute desert, there are locations that have never seen a single drop of rain - or at least not since humans started measuring it there.
The people in the state of Meghalaya in northeastern India, close to the border of Bangladesh, probably wouldn't mind sending a little of their precipitation over to South America. The village of Mawsynram is considered the wettest place on Earth, with average annual rainfall of 11.86 meters (39 feet). By comparison, London gets about 65 centimeters (25 inches) of rain per year.
Image: BIJU BORO/AFP/Getty Images
Most populated city on Earth: Shanghai, China
Just over 24 million: That's how many people live in the African nation of Angola - or in the Chinese city of Shanghai. With so many people, the megalopolis is fighting worsening air quality. Increasing emissions from cars and buses, as well as ever more construction projects, contribute strongly to smog.
Image: Imago
Highest navigable lake on Earth: Lake Titicaca
Puma Rock - which is what Titicaca means in the Inca language Quechua - is the highest lake in the world that humans can traverse by boat. Located on the borders of Peru and Bolivia, it also lays claim to another extreme: the body of water with the largest volume in South America. If you visit, definitely visit the Uros islands, which are completely made of reeds.
