Scientists believe that Jupiter has 79 moons, the most in the solar system. This is most likely because Jupiter is more massive, therefore is can hold on to more massive stuff the orbit around it. Additionally, the fact that Jupiter developed further away from the Sun in the formation process giving it access to more objects to grab into its orbit. Jupiter has four very large moons called the Galilean Moons. These moons include Io, Europa, Ganymede, and Callisto.
Io is the most volcanically active body in the solar system. Io’s surface is covered in sulfur in an array of colors. Jupiter’s immense gravity causes tides on the surface of Io. This tidal heating generates enough heat for volcanic activity and to drive off any water. Io’s interiors consist of a core, and a mantle of partially molten rock, topped by a crust of solid rock covered with sulfur compounds.
Europa’s surface is mostly made of water ice. There is evidence that it may be covering an ocean of water of slushy ice underneath it. There is no cratering on the surface of Europa signifying the surface is relatively young. Europa is heated by tidal heating to the point that the craters are filled with liquid. This moon is very interesting to astrobiologists because the properties and conditions of Europa suggest that it may be a habitable zone where life can prosper. Europa has a core, a rock envelope around the core, a thick, soft ice layer, and a thin crust of impure water ice.
Ganymede is the largest moon in the solar system. It is larger than the planet Mercury. It is the only moon known to have its own internally generated magnetic field. Ganymede has a core, a rock envelope around the core, a thick, soft ice layer, and a thin crust of impure water ice.
Callisto has a heavily cratered surface that is ancient. There is a very small degree of current surface activity. The layering of the interior of Callisto is not very defined and appears to be a mixture of ice and rock.