Last week we explored some of the more fanciful beliefs people have about our closest solar system neighbor, the moon.

This beautiful orb when it rises full is a stunning object and has been the subject of romanticism, legend, superstition and wonder for thousands if not millions of years.While our ability to travel there has removed some of the moon's mysteries, there is still much we do not know about our neighbor, such as how it became our satellite.A couple of the more fanciful theories we discussed last week include the idea the moon is hollow and is a ship. Both of these are based on the idea that the moon has some type of extraterrestrial intelligent origin and is used as a basis of operations by extraterrestrials.There really is no hard scientific basis for these beliefs, but they are interesting ideas. To discuss these theories, let's review a few of the facts about the moon. First it is less dense than the Earth. While the Earth has a large iron core, the moon apparently does not, and that creates the deficit in the density.Second, scientists theorize the moon may have been closer to the Earth at one time and eventually orbited away to its current location, but it still moves slightly away from our planet.Finally, the moon may be as old as the Earth, according to samples that were retrieved from by the Apollo missions and carbon dated by scientists.After having done research on the subject, I will do my best to share what I have learned. One of the earliest theories is that the moon was a part of the early Earth. As the forming planet revolved around the sun, it was also spinning much faster than it does today.This violent spinning forced the Earth to become stretched to the point where part of its mantle broke away and the separated mass fell into orbit around the Earth and eventually formed into the moon. The area of the planet from which the moon separated is the present day Pacific Ocean. This theory is called the fission theory.After we traveled to the moon, scientists realized the composition of the moon was much different from the Earth and much less dense.The idea of a large part of Earth's mantle and core did not fit what they discovered since the Earth has a heavy iron core that comprises 30 percent of the Earth's mass while the moon's core was only 3 percent of its mass.Instead, the composition of the moon samples indicated the moon was much more similar to the Earth's mantle instead of its core. If a large part of the Earth was "thrown off" as described by the first theory, the core should have gone with it but did not. Another issue is the crust under the Pacific Ocean is much younger than the moon.Before the Apollo missions, another theory began to gain traction. In this theory, the Earth captured a rogue planetary body and that became the moon.While this could explain where the moon originated, it does not explain if it was a wandering planet why it lacks a dense core like most of our planetary bodies. If the moon wandered into Earth's orbit, scientists theorize it would be composed more like a planet and less like the object it is.A different theory was derived to help explain why the composition of the Earth's mantle and the moon are similar. In this theory, a large debris field began to collide and grow into a pair of orbital bodies around the sun.As they cooled and continued to pull debris into their cores, the bodies formed, eventually becoming the Earth and the moon. This theory is attractive, and when I was in school was the leading idea as to how the moon formed.The problem with this theory is the one of statistics. It seems odd that if all this debris was colliding and forming the two orbs, why the Earth ended up with all of the rich minerals and the moon ended up with the useless rocks. That seems mathematically unlikely.There is a theory that explains how the moon might be missing the dense metals the Earth's core has, yet still contains much of the Earth's mantle composition. It also explains how the moon ended in orbit around the Earth as well as why the angular momentum of Earth, which is different from most other bodies.This theory is called the "impact theory." In this theory, a small planet the size of Mars ventured too close to Earth early in its development while the Earth was still hot and forming. The planets had a glancing collision, which destroyed the smaller orb, causing it to disintegrate, shattering part of the Earth's mantle off into orbit.The debris from the other planet along with a large part of the Earth's mantle accumulated until it formed the moon. As the moon grew larger, it also started to move away from the Earth until it reached its current orbit.While all of these theories have missing pieces and unanswered questions, the evolution into the final "impact" theory is a fascinating exploration as to how scientific theory grows and changes through the years, taking decades if not centuries to refine and improve.This is a good example of why one should not rush scientific theories into accepted laws or facts because what one believes today may not be correct tomorrow.Till next time …