Well , the astrounauts who ''went to the moon'', said they found another kind of rock who only exists on the moon , that there wasn't such a rock here on the planet earth , it was also used to proove they really landed on the moon surface , but if this rock only exits on the moon surface , it means that the moon couldn't have been created through a collision , between the earth and another object , so it means at least for me , that the moon , came from far away , from outside the solar sytem , and them it got trapped inside the earth gravity , It's what I think.