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
Callisto, Jupiter's moon-Spectacular! According to NASA, it has the darkest surface of the four Galilean moons, but is twice as bright as our moon :) It is also the most heavily cratered object in the entire solar system!