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          \title{The Solar System beyond Neptune}
\author{David Jewitt \\ University of Hawaii}
\date{}


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In this review talk I will describe the properties of the
trans-Neptunian solar system, as discerned from recent ground-based
observations. Twenty-three trans-Neptunians have been identified at the
time of writing (May 1995), mostly from on-going surveys conducted on
Mauna Kea. These are the first detected members of a trans-Neptunian
swarm that comprises about 35,000 objects larger than 100 km in the 30
- 50 AU heliocentric distance range. Vast numbers of smaller objects
may also be present, as well as large but more distant objects that are
too faint to detect.

The dynamical natures of the new objects fall into at least two groups.
About half of the new objects (1992 $QB_1$, 1993 FW are prime examples)
have orbits of low eccentricity with perihelia beyond 40 AU, and so are
relatively immune to Neptune perturbations. These objects, as well as
the distant 1994 $ES_2$, 1994 $EV_3$ and 1994 $JQ_1$ (heliocentric distances 46,
45 and 43 AU, respectively) are likely members of the predicted Kuiper
Belt. Other  objects at smaller distances (e.g. 1993 RO, RP, SB, and
SC) appear to occupy the 3:2 mean-motion resonance with Neptune. They
are presumably dynamical analogues of Pluto, which occupies the same
resonance. Other resonances (e.g. 4:3) may be occupied by
trans-Neptunian objects in our sample.

We will present the observational status of the solar system beyond
Neptune and discuss the impact of this region on theories for the
origin of comets and the growth of planetesimals. 

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