Callisto Facts

Callisto is the second biggest satellite of Jupiter, and the third largest moon of the entire solar system. It is the fourth Galilean moon of Jupiter. In 1998, evidence in the form of underground fluctuations in the moon's magnetic field gave rise to the possibility of a massive lake of salt water underneath the moon's surface. There is also a large amount of water in the form of ice, it accounts for around half of the moon's composition. Callisto is currently being considered as a candidate for future extraterrestrial colonization by NASA.