Giant Impact Theory The moons formation isn't clear to this day, although it does have many theories on its formation. The moons biggest theory is the Giant Impact Theory, which states that a mars sized object strikes earth breaking pieces off, and the gravitational force combines the broken pieces of earth into one, which is known as the Earths moon. The Earths and moons mantle are exactly identical, supporting the impact theory ("Origin of the Moon"). The moon doesn't have any identical features and composition like anything else in the solar system besides planet Earth. Although there are many other theories, the big Impact Theory has the most evidence to support it.
