Pluto isn't the first planet to be demoted, if we stuck by your definition we would have dozens of planets: http://en.wikipedia.org/wiki/Planet#Former_planets h

Pluto isn't the first planet to be demoted, if we stuck by your definition we would have dozens of planets: http://en.wikipedia.org/wiki/Planet#Former_planets http://en.wikipedia.org/wiki/Planet#Former_planets