I was listening to a back episode of Coast to Coast AM from over the holiday week, and the guest who was on the show was discussing the idea of a hollow moon, something I heard about and dismissed many years ago. I have to admit though while I found the theories the gentleman purported to be interesting, I am still not convinced that his beliefs are accurate.

I decided to do some research to figure out where this theory may have originated, and I will attempt to portray both perspectives fairly. Take this as a morning diversion and remember, these are primarily opinions and definitely do not reflect my beliefs nor those of anyone else I know. I just find it fascinating.As most of you know, the moon is our companion as we revolve around the sun. It controls our tides and provides a constant variation in our night sky. It creates eclipses of the sun and we create lunar eclipses every so often on its surface. It has been with us through thick and thin so much that most of us probably do not even give it a second thought especially since we have virtually ignored it after the series of Apollo missions which landed on it.There has been so much speculation about the nature of the moon and some fanciful thoughts about its role in our lives. I wrote a column years ago about this first interesting aspect of the moon.There are amateur astronomers and speculators who will claim after having watched the moon and photographed it daily that there are manmade-type structures on the moon which change, appear and disappear over the course of months. Typically these claims are accompanied by grainy, overcorrected images of the moon's surface in which anomalies are pointed out as "structures" on the surface of our lunar neighbor.When one looks at in-focus, unenhanced, uncorrected photos, these anomalies are not found at least not on the photographs I have seen.Accompanying this belief is one in which some folks purport the moon to be a hollow satellite that was moved into position around the Earth for some apparently nefarious purpose whether it be spying, human abductions or just observation. These proponents claim the moon is less dense for some reason than the Earth and that it resonates indicating the moon is a hollow object. Why would the moon be hollow and placed in our orbit? Well there are some answers given for that question but those believers.One of the most popular beliefs are that UFOs originate from our moon and use its interior as a base. They claim that beneath the moon's surface is an entire civilization kept secret from us. These inhabitants are the ones that visit us in their spaceships and monitor our civilization.Of course if that is the case, one would think that with all the amateur astronomers and telescopes focused nightly on the moon, we would see the comings and goings of such a parade of craft, but we do not nor have we ever recorded such things, to the best of my knowledge. The idea that an alien race is using the interior of the moon as a base while intriguing does not seem too solid.I was doing some background reading on a site called AboveTopSecret.com, and from what I can tell, one of the "pieces of evidence" used to support the hollow moon theory was a statement made by a scientist after observing some instruments left behind to measure seismic activity when Apollo 13 left the surface.The vibrations from the lunar module taking off caused the surface of the moon to reverberate for almost an hour, and a scientist described it as "it was ringing like a bell." What the scientist meant was that the force from the lunar lander that was used to lift off the moon's surface caused a reverberation in the rocks, making them vibrate much like a hammer does on the surface of a bell. Solid objects will reverberate like hollow objects, but with different frequencies and periods.Unlike the Earth, which has a great deal of loose sand, dirt, water and an atmosphere that all act as dampers to quickly stop seismic vibrations, the moon is a lifeless, solid mass with a density less than our planet. Without these dampening agents, a strike on the surface of the moon or a quake from within the moon's mantle would cause that solid, rocky surface to vibrate for quite a long time before it settles.While proponents of a hollow moon would claim the "ring a bell" comment indicates the moon is hollow, the scientist who made the comment really was not intimating that at all. All he was pointing out was that the moon will resonate quite a bit longer than the Earth.He should have added that it was due to the lack of substances to deaden the vibration. So this quotation really does not support hollow moon theory after all.If you investigate this further, there is also quite a bit of speculation as to the mathematics of the moon's density, and when compared to Earth's it seems to indicate that for its size, the moon is missing quite a bit of mass.Without getting into complex calculations, the skeptics of this mathematical comparison point out the composition of the Earth and the moon are not exactly the same. Some of this is due to the way the moon may have been formed, according to theories which I will explore next week. Scientists believe the composition of these two planetary bodies, while similar, have some differences.Next week we will look at where the moon may have originated. More theories.Till next time …