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.
These computer simulations are served up by the free Web-based software program Celestia, which features graphics so convincing that you feel as if the age of space tourism has arrived. Better yet, in the digital universe of Celestia, anyone can be ...
