UREY PRIZE LECTURE - ON THE DIVERSITY OF PLAUSIBLE PLANETARY SYSTEMS

Models of planet formation and of the orbital stability of planetary systems are used to predict the variety of planetary and satellite systems that may be present within our galaxy. A new approximate global criterion for orbital stability of planetary systems based on an extension of the local resonance overlap criterion is proposed. This criterion implies that at least some of Uranus' small inner moons are significantly less massive than predicted by estimates based on Voyager volumes and densities assumed to equal that of Miranda. Simple calculations (neglecting planetary gravity) suggest that giant planets which accrete substantial amounts of gas while their envelopes are extremely distended ultimately rotate rapidly in the prograde direction. (C) 1995 Academic Press, Inc.