Titan: Observation, Measurement & Evidence

Titan's atmosphere is mostly nitrogen with methane and complex organic haze. Its surface includes equatorial dune fields, icy highlands, channels, and hydrocarbon lakes concentrated especially near the poles. Beneath the water-ice crust, interior models allow layers containing high-pressure ice and liquid water.

Cassini radar mapped surface features through the haze, infrared observations identified clouds and composition, and the Huygens probe directly measured atmospheric structure during descent and imaged the surface after landing. Radar-dark and radar-smooth polar regions correspond to hydrocarbon seas.

Sunlight and energetic particles break methane and nitrogen molecules apart high in the atmosphere, driving organic photochemistry and haze formation. Methane cycles between atmosphere and surface through evaporation, clouds, rain, runoff, and lakes in a hydrologic-like cycle operating at much lower temperatures than Earth's water cycle.

Cassini radar penetrated the haze to map terrain and lakes, infrared spectroscopy measured atmospheric and surface composition, and the Huygens probe descended through the atmosphere and photographed a rounded, channel-cut landscape. Atmospheric profiles directly measured temperature, pressure, winds, and composition.