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.] [Illustration: 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.] [Illustration: 11/12/80 128,000 km (79,500 mi) Impact craters on the ancient surface of Rhea closely resemble those on Mercury and Earth’s Moon. Many of the craters have central peaks formed by rebound of the floor during the explosive formation of the crater. Some craters are old and degraded by later impacts. Many have sharp rims and appear relatively fresh, while others are very shallow and have subdued rims, indicative of their antiquity. White areas on the edges of several of the craters are probably fresh ice exposed on steep slopes or possibly deposited by volatiles leaking from fractured regions. Surface features as small as 2.5 kilometers (1.5 miles) in diameter are visible.] [Illustration: 11/9/80 4.5 million km (2.8 million mi) Titan is a large, bizarre satellite. It is larger (almost 5120 kilometers or 3180 miles in diameter) than the planet Mercury and possesses a dense atmosphere of unique composition. Voyager 1’s cameras show Titan’s surface to be totally obscured by a thick layer of atmospheric haze. In the full-disk photograph, only two features are visible: a faint boundary between the southern and darker northern hemispheres and a dark “hood” overlying Titan’s north polar region.] [Illustration: 11/12/80 435,000 km (270,000 mi) This hood and greater detail in the haze layers are shown in the higher resolution photograph.] [Illustration: 11/10/80 4.6 million km (2.8 million mi) Little detail can be seen in this distant view of Hyperion, the satellite which orbits just beyond Titan. Voyager 2 will observe Hyperion at a closer range.] [Illustration: 11/12/80 3.2 million km (1.9 million mi)