Ganymede
Ganymede is the largest satellite in the solar system. It is larger in diameter than Mercury but only about half its mass. Ganymede is much larger than Pluto.
Ganymede's surface is a roughly equal mix of two types of terrain: very old, highly cratered dark regions (left), and somewhat younger (but still ancient) lighter regions marked with an extensive array of grooves and ridges (right). Their origin is clearly of a tectonic nature, but the details are unknown. In this respect, Ganymede may more similar to the Earth than either Venus or Mars (though there is no evidence of recent tectonic activity)