Adults today would have been taught in school that there are nine planets in our solar system: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto. The final one of those, Pluto, being the smallest and furthest away from the sun. It was also the last to be discovered, in 1930 by the young American astronomer Clyde Tombaugh. In 2006 however the planet was demoted to ‘Dwarf Planet’ status by the International Astronomical Union (IAU) who established a set of criteria for full planet status and decided that Pluto didn’t satisfy them all.
The saga was the subject of a 2009 book by American astrophysicist Dr. Neil deGrasse Tyson, The Pluto Files: The Rise and Fall of America’s Favorite Planet, which focused primarily around the way that Americans felt the need to rally around Pluto and protest the decision to demote an American astronomical discovery to second tier status. The book was featured on The Daily Show with Jon Stewart and appeared on The New York Times nonfiction bestseller list.
The Pluto Files is a 2010 Nova PBS documentary presented by deGrasse Tyson, the author of the book by the same name, it gives an overview of the facts about Pluto and examines the controversy over whether it should or shouldn’t be considered a real planet. It includes contributions from various people including fellow Astrophysicists, historians, and journalists. If you enjoy the documentary then buy the book!