The history of the moon is fascinating. It used to trail the Earth before it crashed into the earth. At least the is the predominant theory. New analysis of rocks from the moon have shown further support for this idea as published in Science.
There will be many more posts about the moon including topics on tides, how life started, how it is slowing the earth down and moving away from us, and how it helped us discover the composition of the sun.
For more on moon formation, this article is great. http://en.wikipedia.org/wiki/Giant_impact_hypothesis#Theia