Fairy circle, Natural phenomenon in Namib Desert, Namibia.

Fairy circles are circular bare patches in arid Stipagrostis grasslands, 2 to 12 metres across, each edged by a ring of taller grass. They occur in a band about 160 km inland from Angola to South Africa's Northern Cape, and near Newman in Western Australia's Pilbara. The bare centres are reddish-orange sand; the surrounding grass forms a pale fringe.

Scientists first documented these formations in technical literature during the 1920s. Decades of research have since generated multiple theories about how these patterns emerge and persist in arid environments.

The circles are known as linyji in the Manyjilyjarra language and mingkirri in Warlpiri, spoken by Aboriginal peoples of the Pilbara in Western Australia, where similar formations were found in 2014. In Namibia the sand termite Psammotermes allocerus was recorded in 80 to 100 percent of the circles studied by Norbert Jürgens, who called the lush grass rims "luxury belts".

Viewing is most rewarding after heavy rainfall when the contrast between dry and wet zones appears strongest. Early morning visits offer cooler temperatures and better visibility for observing the full circular patterns across the landscape.

The circles were first noted in technical literature in the 1920s, and study intensified in the last quarter of the 20th century. In 2014 similar rings were found outside Africa, 15 km from Newman in the Pilbara, Western Australia, where Martu and Warlpiri peoples call them linyji and mingkirri.