Titan has thick hazy skies, rainstorms, lakes, winding river channels, and vast dune fields, all at minus 179 degrees Celsius. The rocks are water ice as hard as granite, the rain is liquid methane, and the sand is dark organic material. This episode explores Saturn's largest moon, discovered by Christiaan Huygens in 1655, which is 6 percent larger than Mercury but only 40 percent of its mass, a fluffy giant likely made of up to 60 percent water ice around a small rocky core.

The hosts explain the giant impact model behind Titan's eccentric orbit, why extreme cold lets it hold a nitrogen atmosphere with 1.45 times Earth's surface pressure, and how UV light shatters methane to create tholin smog and a dual anti-greenhouse and greenhouse climate. They tackle the mystery of why methane still exists when it should have been depleted within 50 m ...