Moon of Jupiter
Callisto
Callisto is a moon of Jupiter and has more craters than almost any other place. Its surface is very, very old and has hardly changed for billions of years.
Fact file
- Type
- Moon of Jupiter
- Diameter
- 4,821 km
- Distance from Jupiter
- 1,882,700 km
- Orbital period
- 16.7 days
- Temperature
- -140 °C on average
- Mass
- 0.018 Earth masses
- Gravity
- 0.13 times as strong as on Earth
- Escape velocity
- 2.4 km/s
- Length of day
- 16.7 Earth days (tidally locked)
Callisto orbits Jupiter.
Interesting facts about Callisto
- Callisto has the most heavily cratered surface in the entire Solar System.
- It lies far enough from Jupiter to be barely affected by the planet's strong radiation.
- Despite being more than 4 billion years old, Callisto shows hardly any geological activity.
Frequently asked questions about Callisto
How big is Callisto?
Callisto has a diameter of 4,821 km. That is about 139% of the diameter of our Moon.
How far is Callisto from Jupiter?
Callisto orbits Jupiter at an average distance of 1.9 million km.
How long does Callisto take to orbit Jupiter?
Callisto orbits Jupiter once every 16.7 days.
How cold or warm is it on Callisto?
On Callisto the average temperature is −140 °C.
Name and discovery
After the nymph Callisto, whom Zeus turned into a bear – in the sky she became the Great Bear.
Discovered in January 1610 by Galileo Galilei.
Formation
Callisto formed like the other Galilean moons but remained less differentiated – a mixture of ice and rock rather than clearly separated layers.
Atmosphere
An extremely thin carbon dioxide atmosphere has been detected.
Exploration
Mapped in detail by the Voyager and Galileo probes; no dedicated mission planned so far.
Compared with Earth
Callisto is slightly smaller than the planet Mercury, but much lighter because of its high ice content.
Other moons of Jupiter
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