11/12/80 700,000 km (435,000 mi)
Dione reveals two distinctly different hemispheres. The photograph shows Dione’s trailing side. Bright radiating patterns are probably rays of debris thrown out of impact craters; other bright areas may be topographic ridges and valleys.
11/12/80 162,000 km (101,000 mi)
Dione’s other hemisphere (mosaic) also has many impact craters—the record of cosmic collisions. The largest crater is less than 100 kilometers (60 miles) in diameter and includes a well-developed central peak. Sinuous valleys (seen near each pole) are probably the result of crustal fracturing in the moon’s icy crust. Dione’s diameter is only 1100 kilometers (700 miles), much smaller than any of Jupiter’s icy moons.
11/13/80 80,000 km (50,000 mi)
Craters stand shoulder-to-shoulder on the surface of Saturn’s satellite Rhea, seen in this mosaic of the highest-resolution pictures of the north polar region. Rhea is 1500 kilometers (950 miles) in diameter and is the most heavily cratered Saturn moon. The largest crater, made by the impact of cosmic debris, is about 300 kilometers (190 miles) in diameter.
