  We report the discovery of the minor planet 2003 VB12 (popularly named
Sedna), the most distant object ever seen in the solar system. Pre-discovery
images from 2001, 2002, and 2003 have allowed us to refine the orbit
sufficiently to conclude that 2003 VB12 is on a highly eccentric orbit which
permanently resides well beyond the Kuiper belt with a semimajor axis of
480$\pm$40 AU and a perihelion of 76$\pm$4AU. Such an orbit is unexpected in
our current understanding of the solar system, but could be the result of
scattering by a yet-to-be-discovered planet, perturbation by an anomalously
close stellar encounter, or formation of the solar system within a cluster of
stars. In all of these cases a significant additional population is likely
present, and in the two most likely cases 2003 VB12 is best considered a member
of the inner Oort cloud, which then extends to much smaller semimajor axes than
previously expected. Continued discovery and orbital characterization of
objects in this inner Oort cloud will verify the genesis of this unexpected
population.
