As you know, I’m sure, Pluto is no longer a planet :( The reason being that the current definition of a planet would not allow Pluto to be included in the planet club. The criteria Pluto lacks is “Clearing the neighbourhood”.
So, what the heck does that even mean? Firstly, it is an informal term that basically means the planet needs to be big enough. Big enough for what? Big enough gravitationally so that small near-by masses in its path are either attracted towards the planet (and pulled into it and add to the mass of the planet or to become a moon to the planet) or the near-by masses are scattered away (they sling shot around the planet in question and vanish off into the distance).
And this is not the case for Pluto. Near-by asteroids are not scattered away or gravitationally “sucked” into Pluto. But is Earth a planet? Earth co-orbits with 10,000 other large masses which have not been attracted to us (thank goodness) and have not been scattered away. An image of all these orbits looks like a Spirograph.
In fact, Alan Stern, (who is leading the NASA New Horizons missions) disagrees with the demotion Pluto got. He makes a good point too about Neptune. That if Neptune was a planet then Pluto should have been scattered away. (Pluto does indeed come inside of Neptune’s orbit around the Sun and so if Neptune is a planet then Pluto should have become part of Neptune, a moon of Neptune or have been scatted far away from Neptune)
Pluto, I don’t care what others say, you’re always a planet to me :)