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See, the Earth wouldn't "clear" it's orbit either or asteroids if it was at a location further than we are now. Interesting article:
The key moment came at the 2006 meeting of the IAU in Prague. The IAU put forth three important criteria for planetary status: 1. A planet orbits the Sun. 2. A planet is massive enough to exist in hydrostatic equilibrium. That’s a fancy way of saying that it is spherical. And 3. A planet has “cleared its neighborhood” of smaller bodies within its orbit. Pluto meets the requirements for the first two categories, astronomers reasoned, but it has not cleared its orbit of smaller bodies. Thus, in late 2006 the IAU gave a present to Pluto — a reduced importance and the designation 134340 Pluto, designating it a dwarf planet (with an asteroidal nomenclature).
Pluto is still a planet in the traditional sense, it has just become a member of a particular class of planets. We now have gas giants, ice giants, terrestrial planets, dwarf planets, and minor planets. There are even weirder exoplanets out there. It's going to be a while before it all gets sorted out.