Ariel

Ariel has the brightest and possibly the geologically youngest surface in the Uranian moon system. It is largely devoid of craters greater than about 50 kilometers (30 miles) in diameter. This indicates that low-velocity material within the Uranian system itself peppered the surface, helping to obliterate larger, older craters. Ariel also appears to have undergone a period of even more intense activity leading to many fault valleys and what appear to be extensive flows of icy material. Where many of the larger valleys intersect, their surfaces are smooth; this could indicate that the valley floors have been covered with younger icy flows. The approximate diameter of Ariel is 700 Km.