The Solar System Wiki
Callisto spacepedia.png

Planet of Origin



Galileo Galilei

Date of Discovery

January 7, 1610

Surface Color

Brownish gray


Porous ice water

Alternate Name(s)

Jupiter IV


Minus: Mean: Max: 80.5K 134.11K 165.5K

Callisto is a satellite belonging to the outer planet, Jupiter. It is one of the Galilean moons, a group of the largest moons in the Solar System that were discovered by Galileo Galilei. Callisto was founded by Galileo Galilei on January 7, 1610, the same day as Ganymede, also a Galilean moon, and the largest moon in the Solar System, was is the oldest moon


Callisto is composed of water ice, carbon dioxide, and other compounds. About one hundred kilometers under the surface of Callisto, there is an ocean, much like any other Galilean moons and other moons of Jupiter.


The surface of Callisto is extremely cratered. There are no signs of volcanism, or any other forms of volcanic activity, or any other signs of surface disrupt. It shows that there have been severe cases of impacts, meaning this moon has an extremely thin atmosphere. The surface is covered with white streaks and valleys caused by these collisions. As these collisions began to pile up, the surface began to become more fragile. And due to the thin atmosphere, Callisto surface became very vunerable to these asteroid impacts. It is believed that in the next 1 million years, Callisto's surface will begin to wear away, causing Callisto to implode on its self.


The atmosphere of Callisto is completely surrounded with an extremely thin layer of carbon dioxide and possibly molecular oxygen. There is also an intense layer called the ionosphere, which is an atmosphere full of active ions that reflect radio waves