Pluto is the only planet discovered by an American. In 2006, during the George W. Bush administration, a group of mostly foreign government employees with generally negative views of the US - mostly astrophysicists, not paleontologists, got together and decided Pluto was not a planet. This by nothing other than their arbatrary, self selected definition.
Some people belive that if Pluto had been discovered by a German or a Frenchman it wold not still be considered a planet by the IAU.
if Pluto had been discovered by a German or a Frenchman it wold not still be considered a planet by the IAU Heck, if it had been discovered by a Mestiza woman in Guatemala, we'd never be able to get rid of it.