Of all the moons of Jupiter, Callisto, Ganymede, Europa and Io tantalize us the most. These alien worlds of ice, fire, desolation and hidden oceans tantalize us with their possibility for extraterrestrial life and human exploration of the outer solar system. Join Robert Lamb and Joe McCormick for a mind bending exploration of the great gas giant's Galilean Moons. (Originally published April 26, 2016)