There is a growing controversy over the IAU's decision (not surprised in the slightest). Including the fact that only a single-digit percentage of the IAU actually participated in the vote. And, of course, this…

From BBC news:

Dr Alan Stern, who leads the US space agency's New Horizons mission to Pluto and did not vote in Prague, told BBC News: “It's an awful definition; it's sloppy science and it would never pass peer review - for two reasons.

“Firstly, it is impossible and contrived to put a dividing line between dwarf planets and planets. It's as if we declared people not people for some arbitrary reason, like 'they tend to live in groups'.

“Secondly, the actual definition is even worse, because it's inconsistent.”

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.

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.

Read the rest here