How I Killed Pluto and Why It Had It ComingBy: Mike Brown The solar system most of us grew up with included nine planets, with Mercury closest to the sun and Pluto at the outer edge. Then, in 2005, astronomer Mike Brown made the discovery of a lifetime: a tenth planet, Eris, slightly bigger than Pluto. But instead of adding one more planet to our solar system, Browns find ignited a firestorm of controversy that culminated in the demotion of Pluto from real planet to the newly coined category