IN the early 16th century's age of discovery, maps of the world were exciting reading for up-to-the-minute Europeans. They changed every few years as new lands were discovered and old lands settled into their proper places. Map viewers gradually learned what latitude and longitude meant, and that a straight line on a map (Mercator's projection) is not always the shortest distance between two places on it.
The null century is a new age of discovery, this time of space, and the world's educated public is learning a new geography of orbits and gravitational fields, a new jargon of escape velocities and...