Pluto used to be a full-fledged planet, and in 2006 it was not. However, the status debate continues, and you can follow a discussion live this evening.
The decision of the International Astronomical Union in 2006 to degrade Pluto to a "dwarf planet" is the focus of a debate at 20.00. EDT (0000 April 30 GMT) by the Philosophical Society of Washington, Washington, DC You can watch live here in the window above or directly from the PSW-Science group.
Alan Stern, the principal investigator of the New Horizons mission, who flew past Pluto in 201
Stern will discuss what he considers a scientific issue in the context of the definition of the term "planet", and he will propose a newer definition that covers rather small bodies like Pluto. Ekers will argue for the definition of the IAU, which has a unique taxonomy for small worlds that lie far outside the solar system in a region known as the Kuiper Belt.
The urge to reintroduce Pluto accelerated after the New Horizons flyby of the object, indicating that Pluto had mountains, vast seas, and other complex features. Stern argues that his geology reminds one of a planet rather than a smaller geology of the world.