- Callisto is the second largest moon orbiting Jupiter and the third largest moon in the solar system.
- It has a diameter of 2,985 miles (4,800 km), which is only 1% smaller than the planet Mercury.
- Callisto is the 8th moon in distance from Jupiter and takes 17 days to make one complete orbit of the
- It orbits Jupiter at an average
distance of 1,168,000 miles
- Callisto orbits beyond Jupiter's main radiation belt.
- Due to its orbit being further away from Jupiter it is not under the same tidal influences as Io, Europa or Ganymede.
- It has the lowest density of any of the "Galilean Moons".
- It could have a similar subsurface ocean to those found on Europa and Ganymede.
- Callisto is the most cratered object in the solar system and has the oldest landscape.
- The moon was discovered in January 1610 by the Italian astronomer Galileo Galilei.
Surface, Atmosphere & Temperature
Callisto's SurfaceCallisto may be rather bland in appearance compared to the other "Galilean Moons" but still has a mysterious looking landscape. Its icy surface is around 4 billion years old with no significant geological changes in that time. It is heavily cratered with rather strange icy peaks.
Callisto's AtmosphereCallisto has an extremely thin atmosphere although unlike Europa and Ganymede it is composed primarily of carbon dioxide. It is now known that all four of the Galilean Moons have some form of atmosphere.
Callisto's TemperatureThe highest daytime temperature on Callisto is around
-108C (-162 F). At night temperatures can reach an even
more chilly -193C (-315 F).
CallistoImage taken by Galileo in 1996 showing Callisto's highly cratered surface, the lighter areas are ice.
Multi ringed impact basinThe rings here on Callisto's surface were created by a massive asteroid impact.
Close up image of Callisto's surface taken by Galileo.
Origin of NameCallisto is named after a nymph from Greek mythology who became a lover of Zeus. See Europa for a more detailed explanation.
Life on CallistoMicrobial life may exist in the thin ocean underneath Callisto's surface. Although the conditions would be far less favorable than on Europa or Ganymede.
Callisto enhanced color view
Surface of Callisto