Science Colloquium
Why Pluto Really Isn't a Planet
Dr. Lorne Nelson
Bishop's University
Friday, September 29, 2006
12:30 - 1:20 PM
Hamilton 302
The big astronomy news this summer is that Pluto is officially no longer considered as a planet. In August the International Astronomical Union (IAU) decided that Pluto is a "dwarf planet" and, as such, joins the ranks of millions of other pieces of rock, ice, and debris that orbit the Sun but are not true planets. Ironically the IAU was considering a motion that would have immediately added three NEW planets to our Solar System and would ultimately have required us to add approximately another one hundred! I will review the history of Pluto's discovery and by examining the formation of our Solar System argue that Pluto should never have been classified as planet but rather as a Trans-Neptunian Object. I will discuss its physical properties and show how fundamental physics can be used to delineate between the largest pieces of rock (e.g., asteroids) and true planets.
