WE ARE USED TO associating the term ‘moon’ with images of barren spheres of rock, devoid of dynamic atmospheres and geological processes; and, for the most part, this isn’t far from the truth. But, there are always exceptions to any rule and Titan is one such example.
Titan is Saturn’s largest moon and the second largest moon in the solar system. It is the only moon known to have a dense atmosphere and is the only body, other than Earth, to have a nitrogen-dominated atmosphere and, like Earth, Titan can also boast lakes and rivers, which are fed by rain deposited by active weather systems. Titan even has deserts complete with shifting dunes.
But that’s where the similarities with Earth end. Titan’s atmosphere might be nitrogen rich, but its next major component is methane. This hydrocarbon forms thick impenetrable clouds that, when battered by solar radiation in the high atmosphere, are broken apart and reassembled into volatile compounds like ethane and propane. It is these hydrocarbons that fall as rain to fill Titan’s methane lakes and rivers of liquid methane.
If that isn’t weird enough, scientists have now detected the molecular building-blocks of some of the plastics we used to make drinks bottles and Tupperware here on Earth: propylene.