Dione's features include heavily cratered terrain with craters as large as 62 miles (100 km) across, moderately cratered plains, lightly cratered plains, and fractured areas. The heavily cratered areas are most common on the trailing hemisphere. Logically, a moon's leading hemisphere should be the more heavily cratered, so it has been theorized that a more recent impact spun Dione around. It has been calculated that bodies as small as those that made 22-mile (35-km) craters on Dione could have spun the moon around to its current position. However, the fact that Dione seems to have spun exactly 180 degrees is a mystery.