‘The other shoe’ is the IAU definition of ‘planet’. They recently formed a committee to come up with a definition that could be applied to all solar systems, and now they are floating that definition amongst their peers, looking for acceptance.
This new definition would yield 12 planets for this solar system, based on current knowledge. Some astronomers think this number could go as high as 24.
Personally, I think the astronomers are missing a key point in defining what is or isn’t a planet. Anyone who looks at the orbit of Pluto (or the Plutons, as the new definition refers to them) and contrasts it with the orbits of the ‘classical’ 8 inner planets, can probably get the point I’m trying to make here. Pluto is clearly not of the same nature as the rest of the planets. It’s orbit describes a body that is more akin to a comet than to a planet. The definition of planet should reflect this.
A planet should first and foremost be formed from the original accretion disk of the star that it orbits, or follow the same orbital pathway that the star’s gravity and spin dictates. Anything of planet size that doesn’t conform to this plane should be referred to as a ‘planetoid‘; of planet size, but not truly a planet.
Of course, this kind of level-headed thinking on the subject would yield no new planets for current and future astronomers to hang their names on, so I’m not looking for any of them to notice the argument at all, human nature being what it is.
Call me old fashioned, but I really think these types of defining moments should reflect the need for clarity, not the desire for self-aggrandizement.