What is a Planet?

Owen Gingerich - Gareth Williams - Dimitar Sasselov In 2006, when the International Astronomical Union voted on the definition of a “planet,“ confusion resulted. Almost eight years later, many astronomers and the public are still as uncertain about what a planet is as they were back then. Tonight, three different experts in planetary science will present each of their cases as to what a planet is or isn’t. And then, the audience gets to vote... is Pluto in or out?