In the desert of northwest Australia, about 10 miles east of the small mining town of Newman, lies a natural wonder. If you fly overhead, you’ll see vast carpets of green spinifex grass, pockmarked by barren red circles, as if some deity had repeatedly stubbed out a cosmic cigar on the parched landscape.
These disks of bare soil are called “fairy circles,” and they’re not unique to Australia—they also exist 6,000 miles away in Namibia. There, the circles number in the millions, and extend over some 1,500 miles of desert. They comprise different grasses but their patterns are the same: low-lying vegetation freckled by circles of empty soil. They almost seem alive, growing and shrinking with a lifespan of 30 to 60 years.
Local people believe them to be the work (or footprints) of deities and spirits. Scientists have tried to come up with more grounded explanations since they first started writing about the circles in the 1920s. Some suggested that they’re the work of grazing ants, or radioactive gases leaking from underground, or poisonous plants that kill off their competitors.
Over the last century, two main hypotheses for the cause of these circles have fought their way to the top of the scrum. The first is from Norbert Juergens of the University of Hamburg, who says that the circles are the work of sand termites. To store water, he argues, these insects eat the roots of grasses within a circular patch, allowing the underlying grains of sand to catch and absorb the falling rain. The result is Namibia’s version of a beaver dam—an engineered reservoir. And according to Juergens, the fierce competition between neighboring termite colonies causes the regular spacing of the circles.