Formation

There are numerous theories about the formation of the moon, but the most acceptable one is the "Big Whack " or "Giant Impact" theory. This theory suggests that the moon form 4.5 billion years ago by a collision between earth and a planet sized object. During a period less than 1 year, the materials from the impact set-out into orbiting around the earth, while its gravity began to bring it together to form the moon. Other impacts went on involving meteoroids.  Collisions continuously melted the moon's surface layer, which lead to the forming of a big "magma ocean". Less dense material like aluminum compounds, where at the very top of the ocean. Still impacts blew out craters in the moon surface causing the shaping of mountains. The largest impact, great basin was carved and formed cracks which lava flowed through from the interior. Estimated, 4.0-3.0 years ago, the impacts from meteoroids lessened in amount. Past millions of years, magma raised to the surface filling the largest impact basins. While cooled it formed huge, flat plains which are darker than the older, lighter highland. Which the interior of the moon momentarily cooled and became geologically inactive.