Callisto is a moon of Jupiter, part of the Solar System in the universe. Jupiter is a planet associated with the Sun, our star, and this space encyclopedia describes the moon’s identity and place in its planetary system.

Callisto is one of the most heavily cratered large bodies in the Solar System. Its ancient surface and evidence for a subsurface ocean make it an important comparison with the younger Galilean moons.

No object-specific chemical/elemental dataset has been verified and imported for this record. This does not mean none is publicly available. Appearance may be imagined; chemistry is not.

Discovery and designation
Callisto was discovered in 1610. JPL credits Galileo. The name and discovery entry identify this particular satellite of Jupiter; similarly named asteroids are separate objects.

Callisto is the most heavily cratered object in our solar system.

Callisto is Jupiter’s second largest moon and the third largest moon in our solar system.

Data from NASA’s Galileo spacecraft in the 1990s revealed Callisto may have a secret: a salty ocean beneath its surface. That finding put the once seemingly dead moon on the list of worlds that could possibly harbor life.

Callisto and Jupiter’s three other largest moons were discovered in 1610 by Italian scientist Galileo Galilei.

Almost 400 years later, a spacecraft bearing his name—the Galileo orbiter—began the first in depth study of the Jovian system, including Callisto and its sister moons. Galileo orbited Jupiter until the mission ended in 2003. Since then, several NASA spacecraft, including Cassini and New Horizons, have studied the moon.

Webb Unravels Small Cosmic Details With Interferometry Observing Mode

NASA’s Juno Takes Temperature of Jupiter’s Fiery Moon Io

NASA Samples Antarctic Water to Inform Search for Life on Icy Worlds

Ammonia-Bearing Compounds Discovered at Surface of Jupiter’s Moon Europa

Europa’s Ice Shell (Artist’s Concept)

Images of Callisto from NASA spacecraft.