SOME COSMOGONIC REASONS WHY PLANET-X DOES NOT EXIST

The probability of the existence of a large planet, Planet X, orbiting beyond Pluto-Neptune, is investigated from a cosmogonical standpoint. An extrapolation of the mass content of the pre-planetary nebula indi cates that there is little mass in this region. The planetary accretio n time is also such that the Solar System is not old enough for a plan et to have formed at this distance from the Sun, Thirdly, the pre-plan etary nebula stopped contracting at a finite radius, this being govern ed both by its angular momentum and the enhanced radiation pressure ex erted by the proto-sun as the proto-sun climbed over the top of the Ha yashi forbidden zone. This radius was such that very little material r esided in the trans-Pluto-Neptune regions. It is concluded that the li kelihood of the existence of Planet X is very low.