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Session 69 - Invited Talk.
Invited session, Wednesday, January 17
1st Floor, La Villita Assembly Building

[69.01] Our Current Understanding of the Structure of the Kuiper Belt

H. F. Levison (Southwest Research Institute)

In the last few years, the astronomical community has witnessed a virtual revolution in the understanding of the deep, outer regions of our planetary system. This revolution started with the discovery of the object 1992QB1, which was the first of 28 Kuiper belt objects with radii \sim 100 \sc km that have now been discovered by groundbased observations. When 1992QB1 was discovered, the Kuiper belt was instantly transformed from a theoretical construct used to explain the orbital element distribution of short-period comets to a bona fide component of the solar system.

Since the Kuiper belt was discovered, the amount of data, both theoretical and observational, concerning it has mushroomed. Among the new results that I will discuss are: 1) Dynamical models lasting the entire age of the solar system have been unable to explain the orbital element distribution of the known Kuiper belt objects. Thus, this distribution is supplying us with clues about the formation and early evolution of the outer solar system. 2) The Hubble space telescope has recently discovered very faint (V \sim 28.5) Halley-sized objects in the Kuiper belt. These observations imply that there are at least 200 million comets in the Kuiper belt. 3) Theoretical arguments have strongly suggested that the Kuiper belt was initially much more massive than we see today. This result may put important constraints on the structure of the solar nebula in the outer solar system.

Program listing for Wednesday