9. Uranus' Moon, Ariel

9. Uranus' Moon, Ariel

Courtesy of NASA/JPL

http://photojournal.jpl.nasa.gov/catalog/PIA01356


This high-resolution Voyager 2 view of the terminator of Uranus' icy moon Ariel shows complex crisscrossing valleys with superimposed impact craters. Voyager obtained this narrow-angle view from a distance of 130,000 km (80,000 miles) and with a resolution of about 2.4 km (1.5 miles). Particularly striking to Voyager scientists is the fact that the faults that cross the valleys are not visible in the bottoms of the valleys they cross. Apparently these valleys were filled with deposits sometime after they were formed, leaving them flat and smooth. Sinuous rilles (trenches) later formed, probably by some flow process. Some type of fluid flow may well have been involved in their evolution.