Callisto

Description:
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.

Radius: 2,410 km

Distance to Earth: 628.3 million km

Gravity: 1.236 m/s²

Surface area: 7.30×107 km2 (0.143 Earths)

Did you know: Callisto is surrounded by an extremely thin atmosphere composed of carbon dioxide and probably molecular oxygen, as well as by a rather intense ionosphere.