I don't know if I still have the Scientific American in which I read the article: probably back in the late nineties / early noughts.
Evolution is "just one theory", too. Pretty well backed up theories, though. Moon rock samples taken by the Apollo missions indeed back it up, as well as geological records on Earth.
Earth was hit by a meteor a few billion years ago, just after it formed, and a big chunk peeled off the planet and didn't escape the gravitational pull ...
Edit:
linkie