Many moons, if not most, become a planet’s moon through the capture process. This is a process where the moon would have been formed elsewhere in our solar system as leftover planetesimals. The gravity of the planet could attract the planetesimals and eventually bring it in to orbit with the planet. Upon further research it seems very unlikely that this would have been the case for our own moon. This is because our Earth’s gravity is much too weak to capture and bring into orbit such a large moon.
Other hypothesizes considered that the moon and Earth were originally one planet that had formed together, and separated later in life. Yet the composition of the Earth’s density is much higher than the moon. Thus proving that they we were once not originally one planet.
Today the most support for a hypothesized theory is the giant impact theory. This is an event where a planetesimal, possible as large as Mars, smashed into the Earth. This impact would have probably just as powerful or even more than the KT event. The impact could have blasted layers of Earth’s crust into space. From there that material, with gravitational forces could accrete the debris into our moon as we know it today. Although Earth’s composition is not similar to the moon our crust outer layers are similar. This helps support that the moon was created from a giant impact involving debris of our Earth’s crust. This impact would have had many of the same effects of the KT event, involving a huge dust cloud, turning much of the Earth’s core to molten lava, blowing the Earth off its original axis, and possibly changing the rotation of Earth’s.
