[Saturn and Beyond] consists of a historical description of what we know about the outer parts of the solar system and how we found the information. The author is very careful to indicate what sort of data are still uncertain, such as the sizes, and hence the densities, of the smaller satellites of the outer planets. He also points out fallacies in various theories of the origin of the system, which are apparent if the supposedly measured values are right; and he doesn't try to push us toward a favored choice of his own…. The book is sufficiently up to date to have the information on Pluto's moon, though the author either missed or didn't trust the radar evidence that the particles in Saturn's rings are about snowball size (I'm not sure how far I trust it myself). I caught only one slip; it is true that eclipses of the sun as seen from Titan occur in roughly one quarter of that satellite's revolutions, but Asimov does not indicate that they are not randomly distributed in time. When Saturn is close to its equinox, they occur in every revolution; when it isn't, they don't occur at all. There are numerous useful tables for science-fiction writers, which tell how big and bright the sun looks from various planets and how big and bright the planets look from their various moons. I'm keeping the book; I can figure out all these things for myself, but why should I work harder than I have to?