Titan is Saturn’s largest moon and the only moon known to have a dense atmosphere.
Titan’s atmosphere is composed mainly of nitrogen, with methane as the second-largest component. Its atmospheric pressure at the surface is higher than Earth’s, and sunlight drives chemical reactions that create an orange haze of complex organic compounds.
The moon’s surface includes lakes and seas of liquid methane and ethane, river channels, dunes, mountains, and ice-rich terrain. Water ice plays a role similar to rock on Titan because surface temperatures are far below freezing. Beneath the surface, scientists infer the presence of a water-rich internal ocean.
NASA’s Cassini spacecraft studied Saturn and its moons from 2004 to 2017. Its Huygens probe descended through Titan’s atmosphere and landed on the surface in January 2005, the first landing in the outer Solar System. Titan is also the destination of NASA’s Dragonfly mission, planned to investigate its surface chemistry and habitability.