Ganymede
Ganymede is the third of the Galilean moons and is the largest moon in our solar system. It has a diameter of 5262 kilometers, larger than the planet Mercury. Ganymede is only about half of Mercury’s mass, however (Arnett “Ganymede”).
In appearance, Ganymede looks very much like Earth’s moon. However, the dark areas on Ganymede are not plains like they are on our moon. Instead, the dark areas are made up of large grooves and ridges (Lauber 63).
Ganymede gets its fame for not only being the largest moon, but also for being one of the few with an atmosphere. Its atmosphere, thin and composed of oxygen, is much like the one on Europa. One of the most interesting features of Ganymede is that it was found to have its own magnetic field which located inside of Jupiter’s huge magnetosphere (Arnett “Ganymede”).