Moons of Pluto while searching for Plutonian rings. Styx, announced on 7 July 2012, was discovered while looking for potential hazards for "New Horizons". Charon is about half the diameter of Pluto and is so massive (nearly one eighth of the mass of Pluto) that the system's barycenter lies between them, approximately 960 km above Pluto's surface. Charon and Pluto are also tidally locked, so that they always present the same face toward each other. The IAU General Assembly in August 2006 considered a proposal that Pluto and Charon be reclassified as a double planet, but the proposal was abandoned. Pluto's four small
The Pluto Files The Pluto Files The Pluto Files: The Rise and Fall of America's Favorite Planet is a book written by the astrophysicist and Hayden Planetarium director Neil deGrasse Tyson. The book is about Pluto, which was demoted to the status of dwarf planet in August 2006 by the International Astronomical Union, thereby depriving it of its planet-hood. The book also focuses on the fact that many Americans rallied their support for this icy dwarf on the edge of the Solar System because it was discovered by an American. The book was given a good review by Jon Stewart in a guest