Animation of a fly_by of Titan, the largest moon of Saturn. Titan is the largets moon of Saturn and the second largest moon in the Solar System, being more than 5000 kilometres in diameter. It is the only moon with a dense atmosphere, composed largely of nitrogen, and it is the only body other than Earth with liquid on its surface, in the form of lakes of methane, ethane and other hydrocarbons. Titan orbits some 1.2 million kilometres from Saturn.