User blog comment:Waters Knight/Summer Rose & The Moon Theory/@comment-11188061-20131227142748

I have already mentioned before in the Speculation House, but the moon may be the 'product' of Summer Rose's sacrifice, or at least part of it. I don't think she's the one who created it, but I do think that it's a cumulation of sacrifices from a ritual of sorts that's been continued for a very long time.

That's about to change in RWBY's time though.