I’m staring at the Great Red Spot, a giant ruddy hurricane on Jupiter, slowly rotating in front of me as though I were looking through the porthole of a future manned spacecraft. Seconds later, after taking a quick spin around the vast planet, I hover over the volcanoes on the moon Io, as if preparing for descent. Instead, I throttle back to take in the entire moon, which looks like a bruised olive orbiting above Jupiter’s permanent storms. Then I set off for icy Europa, a neighboring moon, and fly over the crater formation of Callanish. As I view the landscapes, text overlays explain the latest theories about them.