 The largest of the moons is Titan, which holds the distinction of being the only moon in the Solar System with an atmosphere denser and thicker than that of Earth.Titan holds the distinction of being the only object in the Outer Solar System that has been explored with a lander, the "Huygens" probe deployed by the "Cassini" spacecraft.The exploration of Uranus has been entirely through the "Voyager 2" spacecraft, with no other visits currently planned.