Watch Neil deGrasse Tyson Tell the Planet Pluto How It Is

The demotion of Pluto from ninth planet in our solar system to mere planetoid has been met with its fair share of detractors--one of whom squared off yesterday against astrophysicist Neil deGrasse Tyson on Late Night with Seth Meyers. And even though the verbal sparring match ended amicably, Tyson left little doubt why our cosmic neighborhood is now (and should be) one resident smaller.