Twelve Planets?
The new ones: Ceres, Charon and Xena. Ceres is an asteroid, Charon is Pluto's "moon", but more of a twin, Xena is a distant ice ball, larger than Pluto, and part of the Kuiper Belt.
The definition of a planet? It must be round and not a moon. Charon doesn't count because the center of gravity of the pair is between them and not inside Pluto.
I think they ought to just cut it off at 8 planets, excluding Pluto.