  It has been observed that binary Kuiper Belt Objects (KBOs) exist contrary to
theoretical expectations. Their creation presents problems to most current
models. However, the inclusion of a third body (for example, one of the outer
planets) may provide the conditions necessary for the formation of these
objects. The presence of a third massive body not only helps to clear the
primordial Kuiper Belt but can also result in long lived binary Kuiper belt
objects. The gravitational interaction between the KBOs and the third body
causes one of four effects; scattering into the Oort cloud, collisions with the
growing protoplanets, formation of binary pairs, or creation of a single Kuiper
belt object. Additionally, the initial location of the progenitors of the
Kuiper belt objects also has a significant effect on binary formation.
