Episode Artwork
This content requires a premium subscription.
Please log in or subscribe to continue.

The History of the Twentieth Century

264 What Is a Planet?

Released: Dec 25, 2021

Ever since the eighth planet, Neptune, was discovered in 1846, some astronomers searched for a hypothetical ninth planet. Clyde Tombaugh discovered the ninth planet in 1930. Or did he?

264 What Is a Planet?: The discovery of Pluto.
00:00:00