Jupiter Moons - Callisto discovered by Galileo Galilei in 1610 using a telescope. It is thought to have oceans of liquid water beneath its crust. about the size of Mercury, is the 3rd largest moon in the solar system. It is more heavily cratered than any other moon in the solar system. Callisto remains as it was when it formed, during the period of intense meteoroid bombardment that the entire solar system experienced
Ganymede A satellite of Jupiter and the largest moon in the Solar System. It is the seventh moon and third Galilean satellite outward from Jupiter. Completing an orbit in roughly seven days, Ganymede participates in a 1:2:4 orbital resonance with the moons Europa and Io, respectively.