Andrew P. Ingersoll: Enceladus: The Hottest Little Moon in the Solar System

The habitable zone was once defined as the place between Venus and Mars where water could exist as a liquid. However, observations by Cassini and other spacecraft have shown that the habitable zone is an archipelago that includes icy moons in the outer Solar System. Encediadus, a moon of Saturn, emits plumes of water vapor and particles of salty ice. Does this mean there is an ocean underneath?

Andrew P. Ingersoll is the Earle C. Anthony Professor of Planetary Science at Caltech.