Back in the 1950s, I wrote a series of six derring-do novels about David "Lucky" Starr and his battles against malefactors within the Solar System. Each of the six took place in a different region of the system and in each case I made use of the astronomical facts-as they were then known. Now more than a quarter-century later, these novels are being published in new editions; but what a quarter-century it has been! More has been learned about the worlds of our Solar System in this last quarter-century than in all the thousands of years that went before. LUCKY STARR: AND THE MOONS OF JUPITER was written in 1956. In late 1973, however, the Jupiter-probe, Pioneer X, passed by Jupiter and recorded an enormous magnetic field containing dense concentrations of charged particles. The large satellites of Jupiter are buried in that field and the intensity of radiation would certainly make it difficult or even impossible for manned ships to maneuver in their neighborhood. Lucky's trip through the satellite system would have to be adjusted to take the intense radiation into account if I were writing the book today. And in 1974, a 13th satellite of Jupiter, was discovered, a very small one only a few miles across, with an orbit quite similar to that of Jupiter-IX. I'd have mentioned it if I were doing the book now. I hope my Gentle Readers enjoy the book anyway, as an adventure story, but please don't