The Arkenu Craters in northern Africa are shown in this image. Arkenu 1 and 2 are double impact structures located in eastern Libya in the Sahara Desert. Their respective diameters are approximately 6.8 and 10.3 kilometres. The craters are unusual in that they both exhibit concentric annular ridge structures (white circles in the image outline the position of the outermost visible ridges). In many terrestrial craters these features are highly eroded and no longer visible.