Stuff You Missed in History Class

Pluto: The Demoted Dwarf Planet

July 22, 201329 min
It was the only planet to have been discovered by an American, but it's no longer classified as a planet. Who found Pluto, and how did astronomers even know to look for the so-called Planet X on the edge of our solar system?

Chat About Pluto: The Demoted Dwarf Planet