I have to admit that I’m still not used to the designation of Pluto as not a full planet — if only because the mnemonic I was taught as a kid doesn’t really work without it: “My Very Easy Method Just Speeds Up Naming Planets”. (Also the one me and my dad came up with for my homework: “Many Very Energetic Mice Jump Straight Up Never Pausing.”) Darn the people who stole Pluto from us!
(Although actually, it’s still a planet — it’s just a dwarf planet now.)
However, people are still arguing about this definition, for various reasons. Some want to reinstate Pluto on the grounds of its geology, citing the fact that Pluto is large enough to have formed a sphere under its own gravity, which some argue allows for the underground ocean, multiple layers of atmosphere, evidence of past lakes and multiple moons. Some of this would, of course, let in a bunch of other objects in the Solar System… say about 100. Others say that the rule that disqualified Pluto in the first place is being selectively applied: if the requirement is that the planet must be able to sweep its orbit clear, then Earth, Mars, Jupiter and Neptune are also disqualified, because they share their orbits with asteroids.
Good enough for me! Pluto’s a planet. Hurrah.