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Emi Koussi Volcano and Aorounga Impact Crater in Chad are featured in this striking image photographed from the International Space Station. The two circular landscape features show craters produced by very different geological processes. At left, the broad grey-green shield volcano of Emi Koussi is visible (its 3,415 m summit is the highest in the Sahara region). The circular Aorounga Impact Crater is located approximately 110 km to the southeast of Emi Koussi and has its origin in forces from above rather than eruptions from below. The Aorounga structure is thought to record a meteor impact approximately 345-370 million years ago. Image courtesy of NASA.