The moon is one of the many things in our night sky that has managed to intrigue humans for centuries. The moon has various myths associated with it such as lunar madness, man on the moon, and of course moon cheese. The moon has also been used by some cultures to know the time for crop harvesting and the passing of time in months or moons. Even though we have studied the moon in great detail, landed on the moon, and even conducted various experiments, we still cannot determine the origin of the moon. This is a simple case of we weren’t there to see it’.
There are various theories as to how the moon was formed or created. Basically, there are four major theories currently being debated on the scientific arena. Please be aware however that all of these are speculation and not the absolute fact on the matter.
The first theory states that the moon was formed the same time as the earth out of dust, gas and rocks that clumped together out of the same primordial accretion disk when the solar system was first formed. This theory is known as the Co-Formation theory and has a few flaws. Firstly, if the earth and the moon were formed out of the same accretion disk, this would not explain the depletion of metallic iron in the moon and the high angular momentum of the moon and earth.
The second theory is called the capture hypothesis. This theory states that the moon was formed elsewhere in the galaxy but was subsequently captured by the earth’s gravitational field. This theory can be easily accepted by those who do not study astronomy but are merely amateur stargazers. However, when you study it closely you will see that for this to happen, the earth would need an extended or bigger atmosphere to dissipate the energy from the moon. This as astronomers know cannot be the case.
As for the third theory, which is much less believable, is the fission hypothesis. It states that as the earth was forming, it was spinning extremely fast thus causing a big chunk of material to be flung out of the earth (possibly, where the Pacific Ocean is) and into space. This theory fails to explain however, why the moons orbital tilt is not in line with the earth’s equatorial plane. The initial spin of the earth to cause that much mass to be flung out of the earth is too outrageous to be contemplated and has thus far been discredited.
The final theory and the best one so far is the Giant Impact hypothesis. When the earth was young and moonless we can call this earth Mark I- a massive body or planet the size of mars labeled Theia’ collided with earth Mark I and proceeded to throw out a huge chunk of matter into space. While the Earth Mark I and Theia were fusing together, the lump of ejected matter created a temporary ring outside of the rouche radius. The rouche radius is a hypothetical radius in which anything outside it will be become a satellite and eventually be lost to earth’s gravity and anything inside will form a ring and will one day shrink into nothingness. When this lump of matter was outside of the rouche radius, it began to clump together to form a small satellite we now know as the moon. While this was happening Earth Mark I and Theia fused together to become Earth Mark II the earth we now know today.