I have to agree that Pluto is in fact not a planet, as it's not solid in any way...but by definition it should be classified as a planet.
"A nonluminous celestial body larger than an asteroid or comet, illuminated by light from a star, such as the sun, around which it revolves."
Pluto is nonluminous, larger than an asteroid or comet, is illuminated by light from the Sun, and revolves around a star (the Sun).
But I guess they do have some rationalising data against it....I'm kind of a science buff.
