Callisto is the second-largest moon of Jupiter, after Ganymede. It is the third-largest moon in the Solar System after Ganymede and Saturn's largest moon Titan, and the largest object in the Solar System not to be properly differentiated. Callisto was discovered in 1610 by Galileo Galilei.

View on Maps: google.com/maps/space/callisto

Radius: 1,497.7 mi

Orbital period: 17 days

Distance to Earth: 390.4 million mi

Surface area: 7.30×10⁷ km² (0.143 Earths)

Did you know: The Galilean moons are the four largest moons of Jupiter–Io, Europa, Ganymede, and Callisto.