Moon and Earth

Photo by NASA: Image of the Earth and Moon

By Scott Hamilton

I read an interesting, scientific-based conspiracy theory this week that suggest that the moon is a hollow sphere, with a metal layer just below the surface. These claims are based off of a few facts taken out of context, but it makes for a really cool discussion on scientific principles and how even science can be manipulated to tell a different story. The first of the facts these people used to prove that the moon is hollow was based off of experiments conducted by NASA during the Apollo missions.

If you are like most people, you probably think the main reason we went to the moon was to prove that we could do it, and secondarily to study the composition of the moon. There was a little more to the lunar exploration than just visiting the surface and bringing back rock and soil samples. Though the main purpose of the lunar modules was to transport people to the moon, on the successful departure from the moon, the spent modules were sent back to the surface for a controlled crash. The purpose of the crash was to create a seismic event on the moon, or a moon quake.

You might wonder why we want to create a moon quake, but it is really quite simple. Just like we use sound waves in an ultrasound to see an unborn baby, we can use controlled quakes to “see” inside the surface of a planet or moon. There were extensive studies completed on Earth that scientists thought could be directly applied to the moon, but they got an unexpected surprise.

On Earth, if you create a small, controlled earthquake, the vibration dies down in a matter of seconds, or minutes at the most, but when they crashed Apollo 12 into the lunar surface 40 miles from its original landing site, the impact hit with a force equivalent to one ton of TNT. The resulting shockwave built to peak in eight minutes, but did not fully dissipate for a full hour. A similar incident occurred with Apollo 13, but in this case the moon vibrated for nearly four hours. It was described by the scientists as the moon ringing like a bell. These strange results triggered scientists to think differently about the lunar composition. One of the leading theories was that there were large caverns beneath the surface of the moon, intensifying the vibrations.

The second scientific observation on the moon was the fact that a majority of the craters on the moon appear to be nearly the same depth, regardless of the size and force of the impact, almost as if the object that caused the crater hit a solid surface that it failed to penetrate. It is this second fact that has led to the theory that the moon is an ancient alien spacecraft in orbit around the Earth for exploration purposes. Of course I could understand such a claim if there were any detectable signals coming from the moon, but sadly these do not exist.

So this leads us to the question of why the moon rings like a bell when it is struck by an asteroid, or a spent spacecraft. It took several years for us to understand the phenomenon. We conducted studies of the seismic activity on the moon from 1972 to 1977. They read 28 shallow quakes as high as 5.5 on the Richter scale. On Earth these quakes move heavy furniture and crack plaster walls, but stop in a matter of minutes. On the Moon these same sized quakes lasted for hours and even days. So what causes the quakes to vibrate longer on the moon? It comes down to a lack of water on the moon to deaden the vibration.

You can do a little experiment for yourself to see this in action. If you take an empty wine glass and tap it gently with a spoon, it will ring like a bell. Take the same glass and fill it with water and you cannot get the glass to ring. The same thing happens on the Earth; the water deadens the vibrations, preventing the ringing effect. So really the only thing these strange seismic events prove is that there is no water on the moon. As for the reason behind the apparent shallow craters, I do not have the answer, but it seems to be an interesting topic for research. Maybe next week.

Stay safe and learn something new.

Scott Hamilton is an Expert in Emerging Technologies at ATOS and can be reached with questions and comments via email to or through his website at

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