The essentials about Ganymede (Jupiter’s moon)
Diameter: 5,262 km
Ganymede orbits Jupiter in about 7 days. It is the largest moon in the solar system. It is the third of Jupiter’s main moons and, given its distance from the planet, it has an orbital resonance ratio of 1:2:4 with two of the other satellites of Jupiter, Io and Europa.
Ganymede has a core of molten iron and, thanks to it, it has a magnetosphere. It has a thin atmosphere composed mainly of oxygen. Ganymede has many craters due to the impacts of asteroids during its 4 billion years of history, mainly in its darkest areas.
This suggests that the brighter areas are or have been renewed, surely thanks to the action of plate tectonics which reshapes the surface under the effect of the constant heating caused by the tidal forces generated by the gravitational pull of Jupiter.
Image by National Oceanic and Atmospheric Administration / Public domain