Titan is Saturn's largest Moon, the sixth from Saturn, and the second largest moon in the solar system. Its radius is 2575 kilometers, about 50% of the Moon's and its mass is 1.8 Moon masses or 0.022 Earth masses. Its density suggests a significant amount of water in the mass, perhaps with underground oceans.
Its orbit and rotation are 16 days, matching Saturn's rotation and its "seasons" are due to Saturn's orbital Eccentricity (e). Its Atmosphere has a pressure of about 1.45 Earth's and its atmospheric circulation tends to a single Hadley Cell extending from the equatorial to the polar region.
The thick atmosphere was first suggested by observations of limb darkening in 1903. It has an opaque layer (clouds) obscuring the surface. It extends much further than Earth's atmosphere due to the lower Gravity. The stratosphere has been analyzed, presumably through Absorption Lines, and is more than 98% Nitrogen (N), with much of the rest Hydrogen (H) and Ammonia (NH3). Evidence has been found in the ionosphere for heavy ions, thousands of times the mass of hydrogen. The atmosphere and surface also has Methane (CH4), which at Titan's temperatures can be solid, liquid, or gaseous, and which fits a role similar to water in Earth's Hydrology.
TiNy Titans (TNT)