The moon's origin can be explained by a theory called the impact theory.

Yes, this is true. The Impact theory is a theory that the moon is a large chunk of the earth, that had been taken off during the early periods of the solar systems creation. Many believe that this is also why the ocean is so deep and why there is so much water on our planet, that the vast hole that makes up our ocean is just the missing chunk of our planet that became the moon.