PHM Planetarium &
Please note this page is not regularly maintained.
August 2006. New definition for planet ousts Pluto, leaving us with eight planets. A planet is a celestial object that orbits the sun, has sufficient mass for its self-gravity to overcome rigid-body forces so that it is nearly round, and has "cleared the neighborhood around its orbit." A separate category acknowledges dwarf planets. See news at http://skytonight.com/3728231.html.
Copyright ©2003-2008 Chuck Bueter. All rights reserved.