User blog comment:Derrmann/Using the moon to show whether or not trailers were before the series?/@comment-4010415-20131126002436

I'm pretty sure the moon isn't literally falling apart. Monty said the different appearances of the moon has to do with "phases and shit" and that it'll probably be explained further in the show itself.

So, basically, that's just how the moon waxes and wanes.