Pluto has always been known as the 'runt' of the planetary litter..it does not fit the classification of "terrestrial" planets like Earth,Mars,Venus and Mercury that are dense and rocky...nor does it fit the classification of "Jovian" Planets like Jupiter and Saturn that are large, low-density and gaseous...Pluto more aptly fits the description of a small ice-ball.
I can understand why the astronomical community decided it was time to reclassify Pluto as a non-planet since it has properties that are more
"comet-like" rather than planetary.
"Pluto may be the last survivor of a lost population of objects called ice dwarfs that inhabited the primeval solar system." It may be a "distant cousin" Triton, Neptune's moon. Or it may have other "relatives" in the Kuiper Belt, a disk of icy debris left over from the birth of the solar system. Pluto and Triton survive because they have found gravitational positions in the solar system where they remain in stable orbits. Interestingly, Pluto and Neptune are in resonance orbits; Neptune circles the sun three times for every two orbits of Pluto. So, "Pluto never gets close enough to Neptune to be thrown out of the solar system." Triton was captured by Neptune's gravity. The other ice dwarfs that formed within 50 AU from the sun are believed to have been ejected by gravitational interactions with the Jovian planets.
join the Ron Paul Revolution!http://www.ronpaul2008.com/if I could wake up tomorrow morning and push a button and all the AR's would be gone, I would lay awake tonight in anticipation of pushing the button.