AUDIO: The man who killed Pluto

Mike Brown started out trying to find the 10th planet, and ended up destroying the ninth.  

Brown, an astronomer at the California Institute of Technology in Pasadena, began his scientific career dreaming of discovering a new planet.  He spent painstaking years searching the Kuiper belt, the region beyond Pluto, and found many objects — Quaoar, Sedna and Eris to name a few. 

He knew none of these was a planet — they were too small and too insignificant — but they were a lot like Pluto. 

The discovery of these small planetoids spurred the International Astronomical Union to demote Pluto to the status of a "dwarf planet" in 2006. 

Brown spoke to CBC's Quirks & Quarks about the demise of Pluto, which is detailed in his new book, How I Killed Pluto and Why It had It Coming.