Habitability of Planets and Moons

The author takes us to visit Saturn’s moon Titan, and Venus, Mars, and to the unconfirmed planet GJ581d. Although we find unearthly conditions on these bodies’ surfaces today, things were different in the past. Even now, there are oceans deep below Titan’s frozen ice shell that itself sees liquid methane rains and vast ethane-filled lakes. Venus and Mars both had liquid water long ago, while Venus may even have been comfortably warm and humid before modern complex life developed on Earth. Many potentially habitable exoplanets are likely locked in their rotation to always face their star with the same side, causing incredible differences between their day and night sides. This chapter reviews how oceans and atmospheres are lost by the Sun’s magnetism or protected by that of the planets’, how masses of carbon dioxide can be stored in solid limestone, and how habitable zones shift to and from planets.