A Ganymede globe (Jupiter III), the largest moon in the solar system and one of the four large moons of Jupiter also known and as the Galilean Satellites.
With a diameter of 5,268 km to Mars's 6,779 km and larger than Mercury's 4,879 km, had Ganymede not been orbiting Jupiter, it would be the fourth largest solid planet of the solar system.
Had it been near Earth's orbit, it would also be an ocean planet, its rocky core entirely enveloped by an 800km deep ocean. Now as it stands, a vast salty ocean is hidden under a thick frozen exterior.
