Re: What is a moon ?
The IAU definition of planet works fine for purposes of of some scientific fields but not for others and that is its weakness. It is of an ad hoc nature and lacks general utility. Much better would be to pare down the definition to something along the lines of "a planet is a non-stellar object orbiting a stellar object" and then work on classification of the different types of planets much in the way that stellar objects have been.
Even more telling, there is no IAU definition of moon.
Biting the hand that feeds IT
