August 2006 IAU decision:. (Short version) Pluto is no longer a planet.Public Reaction: Not good...What happened?!. August 2006 IAU decision:. (Long version)We\'re going to go back and look at the basics, to try and understand the rationale behind the decision.. What is a planet?. To start let\'s consider this simple question.We\'ll look at the question as a function of history, and how it has been answered in the past..