Callisto is one of the largest moons of Jupiter and the third-largest moon in our solar system. It is known for its heavily cratered surface, which suggests that it has been around for a long time without much geological activity. Callisto is made mostly of ice and rock, and its surface is marked by ancient impacts from asteroids and comets. One of the most interesting features of Callisto is its potential subsurface ocean, which could harbor conditions suitable for life. Scientists are eager to study this moon further, as it may provide valuable insights into the history of the Jovian system and the possibilities of extraterrestrial life.