Back in 1956, Pluto was still a planet and it’s discoverer (Clyde Tombaugh) was in his prime.  Professor Tombaugh appeared on a game show called “I’ve got a Secret”, in which a panel of contestants had to guess his secret.  The answer, of course, was that he had discovered Pluto.  Here is a film of that episode, in which Professor Tombaugh explains to the audience how the discovery was made, and talks a bit about astronomy.  Lots of fun!