Abstrakt
Observations show that 100 km class Kuiper Belt objects (KBOs) can be divided into (at least) two color groups, red (R;g - i 1.2), reflecting a difference in their surface composition. This is thought to imply that KBOs formed over a relatively wide range of radial distance,r.
The cold classicals at 42 au r r*, with 30 au r* r* < 40 au would explain why the VR objects in the dynamically hot population have smaller orbital inclinations than the R objects, because the orbital excitation from Neptune weakens for orbits starting beyond 30 au. Possible causes of the R-VR color bimodality are discussed.