The Kuiper Belt: a Window on the Early Solar System

R. Malhotra (LPI)

A handful of ground-based surveys of the outer Solar system over the last few years have detected several dozen small objects in the Kuiper Belt - or the Edgeworth-Kuiper Belt - beyond the orbit of Neptune, between approximately 30 AU and 50 AU heliocentric distance, implying a population and mass in this region that exceeds that in the asteroid belt by more than two orders of magnitude. Perhaps the greatest significance of this population stems from its connection to the origin of our planetary system: it is likely that the Kuiper Belt contains the most primitive and least perturbed material in the Solar system. An understanding of the dynamical structure of the Kuiper Belt provides the foundation for a quantitative analysis of this connection. Even though the current inventory of detected objects is quite modest, it is already evident that the orbital distribution in the Kuiper Belt is highly non-uniform, with many of the detected objects locked in orbital resonances with Neptune. Their eccentricities and inclinations have a surprisingly broad distribution. Considerations of the origin of these observed properties implicate ``resonance sweeping'' by Neptune as a significant mechanism in the evolution of the Kuiper Belt. Resonance sweeping theory provides constraints on the magnitude and timescale of the radial excursions of Neptune during its early history. We also anticipate quantitative constraints on planetesimal dynamics in the outer Solar system and the formation of the Oort Cloud.