| Ganymede, while larger than our 
							Moon, has a similar 
							appearance - bright and dark areas. The dark areas 
							are older, heavier cratered while the bright areas 
							are newer with fewer craters. However, the surface 
							of Ganymede is comprised of icy rock.
 Ganymede is 
							5,262 km in diameter - the largest moon in our Solar 
							System - and is 1,070,000 km away from Jupiter. As seen earlier, the physiology of Ganymede is 
							very similar to 
							Europa with the exception of the 
							crust. A liquid ocean may lie underneath as evidence 
							of geologic activity on the surface: 
							 
							these stress fractures are the result of possibly 
							water trying to push upward while Jupiter and the 
							other three main moons apply their gravity. 
							 
							The image above also demonstrates the same patterns 
							- notice the impact craters. Other interesting 
							features of Ganymede are a result of outside forces: 
							an impact of what might be a broken object similar 
							to the impact of comet
							
							Shoemaker-Levy on Jupiter. 
							 
							Other surprises include a very strong magnetic field 
							discovered by the 
							Galileo probes, with what might be 
							its own magnetosphere. The core also contains 
							metallic rock similar to
							Europa, and a liquid ocean 
							could enhance the magnetic field. 
							Another surprise, Ganymede does have a very tenuous 
							atmosphere comprised of oxygen and ozone. 
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