Yes, one question I would raise would be the possibility of a double-planet system. Something like Pluto-Charon, though in an orbit bereft of other objects.

It is well-known that they orbit a barycentre - at a point somewhere between the two. In a different orbit, they could IMO well be a double-planet system.

Though I agree that that is hardly an over-riding concern at the moment.

In regards to Neptune's orbital dominance and % of mass in that orbital area, are you including in that figure for Neptune the mass of the plutinos and even perhaps twotinos - that are orbitally dominated by Neptune - even if they do not strictly cross Neptune's orbit?

And what would the figure be if the mass of all the objects in the Kuiper Belt - up to 50AU was included as well as that of those in the exact orbital region?

Another thought, what if the mass of the asteroid belt was included in calculating the figure for Jupiter - as its widely accepted that the presence of Jupiter close to that region prevented the formation of a larger object in that region - so its Jupiter's orbital dominance that creates and maintains the Asteroid Belt.

Would those figures approach the 98% mass dominance enjoyed by the Earth? Or at least under 99%?

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