If Pluto is a planet, so would be Eris, Sedna, Haumea, Makemake, Chorion, and Pallas. So how many planets are in our solar system? 8 (or 9 if you include the one that almost certainly exists in the Kepler belt that is about the size of Neptune) Or 15 (16 once again if you include the highly probable 5th Gas Giant)