I believe in keeping science separate from sentimentality. You don't base decisions on whether one particular age group (or religion for that matter) really, really wants something to be true. So I'm pretty happy to see Pluto kicked to the curb today.
I am concerned, however, about one element of the new definition of a planet: "a celestial body that is in orbit around the sun, has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a ... nearly round shape, and has cleared the neighborhood around its orbit."
The sun? Shouldn't that be a sun (or, more rationally, a star)? I'm hoping this is some kind of misunderstanding on either my part or the AP's. Surely the IAU isn't trying to say that there are no planets outside the Solar System.
Update: Here's the full text of the IAU resolution. Since it names "the eight planets," some have read it to mean exactly what I feared. But I think this part of the preamble, while slightly confusing, ultimately mitigates my concern: "The IAU therefore resolves that 'planets' and other bodies, except satellites, in our Solar System be defined into three distinct categories in the following way..."
The resolution does not say that planets must be in our Solar System to meet the definition; rather, it is only defining those planets that happen to be in our Solar System, leaving open the possiblity not just of other planetary systems but also of other defintions for planets in those systems.
