One point that's come up is that the definition of "planet" that the IAU voted on may exclude the Earth as well!
One of the three criteria for planethood states that a planet must have "cleared the neighbourhood around its orbit". The largest objects in the Solar System will either aggregate material in their path or fling it out of the way with a gravitational swipe.So do we have yet another mess?
Pluto was disqualified because its highly elliptical orbit overlaps with that of Neptune.
But Dr Stern pointed out that Earth, Mars, Jupiter and Neptune have also not fully cleared their orbital zones. Earth orbits with 10,000 near-Earth asteroids. Jupiter, meanwhile, is accompanied by 100,000 Trojan asteroids on its orbital path.
And if even the head of NASA's mission to Pluto is not going to accept the new definition, why should anyone else feel bound by the IAU's decision?