Axes list distances in AU, projected onto the ecliptic, with ecliptic longitude zero being to the right, along the "x" axis).
Positions are accurate for January 1st, 2000 (J2000 epoch) with some caveats:
For planets, positions should be exact.
For minor bodies, positions are extrapolated from other epochs assuming purely Keplerian motion. As all data is from an epoch between 1993 and 2007, this should be a reasonable approximation.
Radial "spokes" of higher density in this image, or gaps in particular directions are due to observational bias (i.e. where objects were searched for), rather than any real physical structure. The pronounced gap at the bottom is due to obscuration by the band of the Milky Way
↑Carl D. Murray and Stanley F. Dermott (1999) Solar System Dynamics, Cambridge University Press ISBN: 0 521 57295.9. ISBN: 0 521 57295.9
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