Many scientists think that the moon was originated when a large meteor hit the Earth, knocking a chunk off of it. The chunk most likely came from somewhere within the current Pacific Ocean. For more...
I heard that the moon first appeared when the asteroid hit the planet and caused the climate change which killed the dinosaurs. - the debris formed together (because that's what gravity does) and the...
About 4.5 billion years ago, as the result of a collision between the proto-earth and another large (mars sized) planetoid in the same orbit as earth. Another view: A little over 7,000 years ago,...