iss012e09639

ISS012-E-09639 (29 Nov. 2005) --- The impact of an asteroid or comet several hundred million years ago, according to scientists, left scars in the landscape that are still visible in this International Space Station/Expedition 12 picture of an area in the Sahara Desert of northern Chad. The concentric ring structure is the Aorounga impact crater, with a diameter of about 17 kilometers (10.5 miles). The original crater was buried by sediments, which were then partially eroded to reveal the current ring-like appearance. Scientists note a number of valleys cut by thousands of years of wind erosion. The area shown is centered at approximately 19.1 degrees north latitude and 19.3 degrees east longitude.