Its a ball of super condensed negative aether that has become solid mass. That's what I think at least. I'm more than likely wrong and it's just a moon to a moon. :3 Myself, I don't actually think that when they say "Meteor" they actually mean a physical piece of rock floating in space, but the process of making something from space crash into the planet being a meteor itself. If that makes any sense, but that's all I have to say.