Pluto's demotion from "planet" status to
"lame Kuiper Belt resident" ahem "dwarf planet"/"planetoid" continues to be the subject of deep nerd rage. Many of us who grew up with Pluto-as-planet feel that modern astronomers are messing with our childhood memories. Others just make shirts and move on.
Today I bring you C.G.P. Grey's beautifully reasoned discussion of why Pluto is or isn't a planet, what the Kuiper Belt is, the history of planets, and (most fundamentally) what the word "planet" has meant over the millennia. Somehow Grey accomplishes all of this in a little over four and a half minutes. Even the nerdiest among us will learn something from this video, and the copy-editors in the crowd may spot a tiny typo at one point -- I'll leave that to for your eagle eyes to spot. Commence the nerd raging!