Well I don't really know anything about space (with the exception of one term spent learning about it in year nine science).
This is the way that I've interpreted what I've been reading about Cruithne tonight. It is a lump of rock that, along with other lumps of rock, moves around the sun. BUT it's orbit is unusually relative to the Earth so that it seemingly is one of it's moons at certain times. But it is not technically a satellite of the Earth.
Anyone can correct me if this is wrong because I'm no expert.
...and I am one of those people who don't.
I'll tell you someone who has some very intelligently formed and regularly genius theories about space; Brian May. I've been reading his blog and he really understands what he's talking about. He should know, seeing as he has a PHD in astrophysics (I think!).