Nearly eighty years ago an astronomer by the name of Clyde Tombaugh, working at the Lowell Observatory, made a discovery that would ultimately initiate a dramatic change in the way we look at our Solar System. IAU members met at the 2006 General Assembly and agreed that the term "planet" is defined as a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for it's self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium shape and (c) has cleared the neighborhood around its orbit. This definition is flawed because every 228 years Pluto crosses inside the orbit of Neptune, so technically Neptune has not cleared it's orbit. Neither has Mars and Jupiter as they "interfere" with asteroids. Earth also orbits the Sun with thousands of Asteroids. Also, why aren't dwarf plants known as Planets? Dwarf stars are still stars, and dwarf galaxies are still galaxies. Help to fight for the reinstatement of Pluto as a "Planet". http://www.look-to-the-skies.com/why_pluto_should_still_be_a_plan.htm