It's interesting the direction the "what is a planet" discussion has gone in... After all the recent talk of possibly 'demoting' Pluto (not that it makes much difference to Pluto what we call it!) they instead propose a definition that not only keeps Pluto a planet, but makes Charon one too, adds Xena (or whatever they're going to call it) and makes Ceres a planet again!

I like the new definition - a planet's round under its own gravitation, and orbits a star and not another planet. Even the bit that gets Charon in and not the Moon makes sense to me, since the point Pluto and Charon are orbiting is outside Pluto, but the Earth/Moon barycenter's inside the Earth. Of course, I'm sure lots of people are going to hate the new definition - they'll propose arbitrary size limits to kick Pluto out or keep Pluto in but kick Ceres and Charon back out, they'll complain there are going to be 'too many' planets, etc. But then I don't think any definition is ever going to make everybody happy! :)

The real question is: What's the new mnemonic for the planetary order going to be? The one I remember is My Very Expensive Machine Just Smashed Up Near Pluto... So maybe with a little modification... My Very Expensive Mini Cooper Just Smashed Up Near Pluto's Cousin Xena/UB313/whatever? That could work!

(There... now we *have* to keep Ceres!)