
The Eye of Africa — whose official name, the ‘Richat Structure’, seems so mundane in comparison — was spotted in central Mauritania by astronauts on early space missions. In the expanse of the Western Sahara Desert, the formation has a diameter of about 30 miles. At first, scientists thought a meteorite had hit the Earth, causing this impression. But now it is believed to be a symmetrical uplift that erosion has revealed. No one has explained yet why it is circular.