You may have heard that the list of planets in our solar system grew by three last week. People of my generation are so used to thinking that there are nine planets in our solar system that it’s always a little weird to look back and realize that there was a time, only a few hundred years ago, when people believed there were only six — or five, if you lived long, long ago and did not consider Earth itself to be a planet. (It’s no accident that the seven days of the week are named for the seven moving objects in the sky — including the sun and moon — that are visible to the naked eye.)
It has been only 76 years since Pluto, the ninth and until recently final planet, was discovered in 1930, right around the time of my grandmother’s 15th birthday. And I wonder if there are any surviving movies from before that period that make explicit reference to there being only eight planets in the solar system. If there are, they would almost certainly be silent films, though by that point talkies had already existed for a few years.
Of course, the most famous reflection in cinema of the discovery of Pluto may be the fact that Walt Disney reportedly named Mickey Mouse’s dog after the newly-discovered planet.Pluto’s first appearance is often dated to The Chain Gang (above left), a cartoon that was released in August 1930, but he was just one of two anonymous bloodhounds who were chasing Mickey Mouse there. Several sources, including the Disney Archives, say the first cartoon in which Pluto actually goes by that name was The Moose Hunt (above right), released in May 1931, but I recently re-watched it — with the subtitles on — and didn’t hear anyone call him that. At any rate, he definitely had that name by the time Mickey’s Pal Pluto was released in February 1933.
Interestingly, some sources claim that Pluto was also briefly known as a dog named Rover who belonged to Minnie Mouse. As it happens, “planet” comes from a Greek word meaning “wanderer”, to reflect the fact that these objects moved in the sky in a way that was out of sync with the stars — and one of the synonyms for “wander” is “rove”. Now isn’t that a neat coincidence.