The underlying premise is that when discovered, Pluto was the ninth planet. Early measurements suggested that it was, in fact, about the same size of Mercury, although perhaps less massive. As telescope images improved, however, we discovered that not only was Pluto much smaller than we thought, but also that it has a moon, which is a good portion of its own mass. In addition, a number of other objects have more recently been discovered around the orbit of Pluto that were almost as big, and now we have discovered one that is even bigger.
Historical precendent holds that Ceres was once listed as a planet, before it was discovered to simply be the largest asteroid in the asteroid belt, one of many, and was in the past, demoted. Should
I vote that Pluto should keep its status, if only out of tradition's sake.
And I add that no matter which side of the fence you sit on, we live in a truly amazing universe!
![Smile :)](./images/smilies/icon_smile.gif)