The largest moon in our solar system, Ganymede is even larger thanΓÇöalthough not as dense asΓÇöthe planet Mercury. GanymedeΓÇÖs surface, with its impact craters and dark areas, is not unlike that of our own Moon. The craters most easily seen in this image are about 150 kilometers around. Ganymede is an old moon; some of its craters are thought to date back about 4 billion years, to the period of most intense cratering activity in our solar system. In addition to the craters, there are huge cracks and faults on GanymedeΓÇÖs surface. Besides the Earth, Ganymede is the only place in the solar system where faults of this type have been observed.
