There actually is a size factor. The smaller 'sun orbiting' bodies are called planetoids, they range from large free asteroids (excess of I think 75 miles in diameter) all the way up to Chiron and Pluto. Many consider both Pluto and Chiron to be planetoids, and not true planets. Satellites, on the other hand, orbit either a planetoid or a planet. I believe there is another sub category of planetites, but I don't hear much about these bodies. They are actually small asteroids, or ice rocks that have free orbits around the sun. Cheers, James. -----Original Message----- From: utah-astronomy-bounces+cyanics=xmission.com@mailman.xmission.com [mailto:utah-astronomy-bounces+cyanics=xmission.com@mailman.xmission.com ] On Behalf Of Rob Ratkowski Sent: Sunday, March 14, 2004 4:55 PM To: Utah Astronomy Subject: Re: [Utah-astronomy] 10th "planet"? Sorry Jupiter has 63 moons http://www.ifa.hawaii.edu/~sheppard/satellites/jupsatdata.html This site for Jupiter by U Hawaii Institute for Astronomy _______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Visit the Photo Gallery: http://www.utahastronomy.com