Aorounga Impact Crater, located in the Sahara Desert of north-central Chad, is one of the best-preserved impact structures in the world. The crater is thought to be about 345-370 million years old, based on the age of the sedimentary rocks deformed by the impact. Radar data suggests that Aorounga is one of a set of three craters formed by the same impact event. The other two suggested impact structures are buried by sand deposits. Image courtesy of NASA.