During the formation of the Moon was attacked by asteroids

That was the motive that the visible side of the moon almost completely covered by seas and plains landforms, and on the other side a lot more hills and uplands. This was proved by Japanese researchers led by Ryosuke Nakamura of the National Institute of Advanced Science and Technology in Tsukuba.

Also they found that most large sea satellite - the Ocean of Storms, - located in the western part of the visible side of the satellite, in fact, is the trace of the fall of a giant asteroid. These conclusion experts came by studying the chemical composition of rocks in it with the tools of Japanese probe "Kaguya".