Titan from space, Cassini image. Titan (5150 kilometres across) is Saturn's largest moon, with a thick nitrogen atmosphere and orange haze. This image reveals the differences in the composition of surface materials around its lakes, which are composed of hydrocarbons such as methane and ethane. Kraken Mare, Titan's largest sea, can be seen spreading out with many tendrils on the upper right. The big dark zone up and left of Kraken is Ligeia Mare, the second largest sea. Below Ligeia is Punga Mare, the third largest Titan Sea. Numerous other smaller lakes dot the area. Titan's north pole is located in the geographic location just above the end of the 'finger' of Punga Mare. Imaged on 12th September 2013, by NASA's Cassini spacecraft.