The Solar System Wiki
Ganymede spacepedia.png

Planet of Origin



Galileo Galilei

Date of Discovery

January 7, 1610

Surface Color

Gray (white geographical features)


Saltwater Ocean

Alternate Name(s)

Jupiter III

Ganymede, also called Jupiter I, is the largest moon in the entire Solar System, the largest of the Galilean moons, and the largest of Jupiter's moons. Ganymede is bigger than the Planet Mercury. This moon belongs to the planet Jupiter, which is ironically the largest planet in the Solar System. Ganymede is one of the Galilean moons, which were discovered by Galileo Galilei. Ganymede was discovered on January 7, 1610.

It is a member of the Galilean moons, meaning it maintains hydrostatic equilibrium, meaning it can maintain a nearly round shape, showing it has a sufficient amount of mass.


A saltwater ocean is believed to exist or have existed beneath Ganymede's surface, but about 200 km deep. The ocean is believed to be sandwiched between different silicate rocky and watery ,icy layers.


Ganymede's surface is mostly covered with rocky caverns and craters from asteroid impacts. The rest of Ganymede is made up of light regions with crosscuts similar to the Earth's moon.

647px-Craters on Ganymede.jpg

Like Father, Like Son[]

Jupiter is the largest planet in the Solar System. Ganymede is one of Jupiter's satellites, or moons, and is the largest moon in the Solar System. In fact, it more than twice the size of the Earth's moon. Ganymede is even larger than the planet of Mercury but 40% of mercury mass

Relatonship with the Galilean Moons[]

The Galilean moons are the most massive and the largest moons in the Solar System, making Ganymede, the largest moon in the Solar System, fit in perfectly. Ganymede, however, contains craters and mountainous areas, differing from the other Galilean moons. Callisto contains larger craters that appear to have crosscuts inside of them. Europa just has plain crosscuts on the surface, and last but not least, Io, has volcanic activity, differing from any moon belonging to Jupiter.