The Moon has been the subject of many myths and legends concerning everything from Werewolves, and Vampires to the reasons why people seem to go nuts during a full Moon. In addition to this the Moon has most assuredly been the cause of many romantic ventures of the heart
However in spite of all this, one thing is for certain, the Moon has been with us from the beginning of the Earth itself, and will probably continue to be with us for at least another few billion years anyway. If you are like me you have viewed the Moon with mixed emotions. In spite of this one thing is for certain, if it were not for the Moon, life as we know it would not exist.
The Moon has guided travelers in the night for centuries. It has been used for planting schedules in Almanacs. And to the ancient races of man it was used for everything – from keeping track of time – to predicting the coming of doom itself.
The Moon controls the oceans tides, which in turn are intertwined deeply in the birth cycles of many creatures that inhabit this wonderful planet of ours. The appearance of the Moon in the skies has always instilled a desire to learn more about it. When Galileo first observed the Moon through his newly acquired telescope, I am sure he fell out of his chair. For to behold the Moon in all its glory for the first time is truly breath taking remember?
Can you imagine Galileo’s thoughts when he first beheld the craters, the great mountain ranges, the battered highlands, and the wide open lowlands? I will even bet that after all this soaked in his first -or at least somewhere in there- question was, how this great marvel came to be. Well, my friends it is exactly that question we are going to discuss in this chapter.
We will begin with a discussion covering the several different theories that have been put forth through the years concerning the Moons origin, and how some of these theories have overlapped in their ideas. Then we will move on to a look at the lunar surface.
In scientific circles these theories are known as “naturalistic” theories, and fall under the category of being either “methodological naturalism” or “philosophical naturalism”. But no matter what you call them they are fascinating by nature and definitely stir the imagination.
The Genesis Theory
In the first chapter of Genesis – in the old testament of the King James Version – there are the verses 14 through 18. These verses describe the creation of night and day and why the lights were placed in them to illuminate the two.
14. And God said, Let there be lights in the firmament of the heaven to divide the day from the night; and let them be for signs, and for seasons, and for days, and for years:
15. And let them be for lights in the firmament of the heaven to give light upon the earth: and it was so.
16. And God made two great lights; the greater light to rule the day, and the lesser light to rule the night: he made the stars also.
17. And God set them in the firmament of the heaven to give light upon the earth.
18. And to rule over the day and over the night, and to divide the light from the darkness: and God saw that it was good.
To those followers of the Godly faiths there is no simple explanation to the origin of the Moon. And to put it in the words of the late Sir Isaac Newton,
“All material things seem to have been composed of the hard and solid particles above mentioned, which are variously associated in the first creation by the council of an intelligent being. And if he did so, it is unphilosophical to look for any other origin of the world or to pretend that it might arise out of chaos by the mere laws of nature”.
The Fission Theory
The fission theory was first introduced in 1878. This theory was the brainchild of George Darwin. George was the son of the famous Charles Darwin – who we remember as the father of the evolution of the species theory. Like his father before him George’s theory was very controversial when it was first introduced, but it was simple in nature.
We know that the Moon orbits around the Earth. As the Moon orbits the Earth its gravitational field causes a reaction on the Earth’s surface. This reaction effectively pulls upon the Earths crust causing it to bulge in two places. This first area of interaction would of course be the Earths crust located directly under the Moon. This would be the point of the greatest influence – or high tide. The second location would be the bulge on the opposite side of the Earth. This would be the point of least influence – or low tide.
Now, due to the fact that the Earth revolves faster than the Moon can orbit around it. The forward momentum of the Earth’s rotation tends to pull the high tide bulge slightly ahead of the Moon. On the other hand, the counter acting gravitational pull of the Moon on the Earth brings about a slight drag on the Earths surface. This drag causes the low tide bulge to be pulled slightly behind the Moon.
Because of this influence of the Moons gravitational pull on the Earth’s rotation. Over a period of billions of years the Earth’s rotation is slowing down. In addition to this the Earth’s gravitational pull on the Moon is gradually getting weaker while the centrifugal force of the orbiting Moon is getting stronger. This results in the Moon moving further away from the Earth, to the tune of one and a half inches per year.
A Trip Back in Time
Now let us take a look at this problem for a moment. If we take the present position of the Earth in comparison to the Moon, then start running time backwards subtracting one and a half inches every year – for say a few billion years. We would find that the closer the Moon gets to the Earth, the shorter its orbit becomes, and the faster the Moon revolves on its axis. In view of this – the tidal effects between the Earth and the Moon start heating both planets to the point of reaching a molten state. As we go further back we see the Earth -because it is in a molten state- start to flatten out into a planetary accretion disc.
As the Moon fuses with it, the two planets become one. So in a nut shell – according to George Darwin’s theory – the Moon being thrown off this rapidly spinning proto planetary accretion disc – seems to illustrate that his theory of the early Earth could very well be true. Or could it?
Two Problems
The first problem with this theory is that according to George it took the Moon fifty four million years to reach its present location. This of course immediately ran into rebuttals from his father’s close friend Lord Kelvin. Lord Kelvin claimed that if rock melted at 2,200 degrees Fahrenheit then the cooling time estimates for the Earth would only be twenty to forty million years, which kind of shot a hole in George’s theory. Fortunately however, thanks to a discovery by the famous Arthur Holmes in 1911 concerning rocks dating 1.6 billion years, could George’s theory now have a little merit after all?
The second problem – and the most damaging – stems from the fact that samples brought back from the lunar landings did not indicate a chemical similarity in samples of the Moon when compared to the chemical composition of samples taken of the Earth. This revelation meant that since these samples did not have chemical similarities. Then the whole idea that the Moon was thrown off by the Earth during the birthing process had no credibility at all – sorry George.
The Co – Accretion Theory
The co-accretion theory actually is the culmination of several theories rolled into one. In the year 1749 a man by the name of George Leclerc claimed that the Earth was 75,000 years old. He also stated that the biblical account of the Earth’s creation in Genesis must be wrong. Fore it would surely have taken more than any six days to create it, unless the six days that were mentioned were simply symbolic of a much longer time frame. Leclerc felt that if a time frame such as the one told of in the Bible were actually meant to be of a symbolic nature, then it could also be possible that the process of creation itself could very well have also been indicative of a more lengthy period of time..
Leclerc went on to say, that in view of the fact that all of the six planets revolve in the same direction around the Sun. It would be highly unlikely that this happened out of pure coincidence. So therefore, Leclerc felt that all of the planets must have been created at the same time as a direct result of a comet impact with our Sun. Leclerc further postulated that this proposed impact threw off molten blobs that would later have cooled – to become the planets that we know today.
Two of the many problems with his theory – is that there is no comet large enough to have caused such an event to occur. The next problem – is that again there are no similarities in the chemical properties of samples between the Earth and the Moon provided by the Apollo missions.
The Collapsing Nebula
In the year 1796 a man by the name of Pierre Simon came up with the theory that in the past there was a very large collapsing nebula that extended as far out from our Sun as the planet Uranus. As this nebula began to compress, it would begin to rotate faster and faster until the gravity produced by the birthing star at its center our Sun – could not hold the outer perimeters of the newly forming nebula in place.
When this happened the outer edges of the nebula detached – then began to cool. The nebula then began to coalesce, and separate into individual accretion rings. Once this occurred, the particles that made up the accretion rings began to coagulate – due to a mutual gravitational attraction in the rings – then began to form planets. Now if this creation theory held true for the solar system, then surely it held true for the formation of our Moon also. Therefore the Earth along with the Moon, and all the other planets came into existence at the same time. Or did they?
A Slight Twist
In the year 1898, Thomas Chamberlain came up with a slight twist on Pierre Simon’s theory. He believed that instead of the planets forming from a hot nebulous cloud, they instead formed from a cold dense spatial material made up of varying sizes of rock mixed with galactic dust. He further postulated that this dense material had been formed from two spiraling jets that had been created from a close encounter between our Sun and a rouge star that had either came to close – or had collided with our Sun in the distant past.
This close encounter between these two stars (presumably the rouge star was much larger) brought about a great tidal effect between these two stars that began to pull material from our Sun – this material was then drawn out into two long spiraling jets that while shooting off in opposite directions, dislodged many globs of matter from our Sun. This matter later coalesced over a period of time into the planets we know today.
This theory was an intriguing one for me, and it did lead to a great deal of debate over the validity of the evidence. As time went on this theory later became the basis of a modern idea that involved basically the same chain of events. The only exception was that this time the players have changed. But, I will hold that as a surprise for later. Right now I want to discuss a man by the name of Thomas J. See. And how his idea of the Moon being taken captive by the Earth’s gravity gained popularity in early years.
The Capture Theory
Mr. Sees’ theory was basically a simple one. In Sees’ theory he believed that space was not a void made up of a vacuum, but rather a void made up of what he termed as a “resisting medium”, which was very much reminiscent of the Greeks idea of the void of space being filled with ether. It was this resisting medium that first began reacting with a proposed rouge planet, which See claimed was moving through our solar system. This rouge planet was pulled into close proximity to Earth by the gravitational attraction of our Sun. As the rouge planet came close to Earth, this “resisting medium” caused enough drag on the rouge planet to slow it down – just enough – for the Earth’s gravitational field to capture it.
Although this theory does sound a little far fetched, some of the ideas put forth did prove viable. One idea in particular was the mention of the resisting medium, which Mr. See described as being akin to Newton’s description of gravity. In the comparison made between the equations provided by Mr. See and Mr Newton. The one provided by Mr. Newton did prove to be more accurate – so much so – that it was used almost a hundred years later by NASA to slow space vehicles before entry into orbit around other planets. This was a method perfected by NASA known as “aero braking”.
One Problem
Mr. See went on to explain, that it was this same process of capture that brought about the existence of all the planets in our solar system.
Now it seems to me that the biggest problem with Sees’ theory was not necessarily the mathematics. But the absurd assumptions that he made with out any scientific data to back it up. This was proven by a mathematician by the name of George Hill. Mr. Hill stated that in the gravitational interactions of a three body system – such as that of the Sun, the Earth, and the Moon. The two larger bodies – the Sun and the Earth – would create interacting gravitational fields. These fields would capture the lesser sized body -the Moon -. However this would only be true if the third body was smaller than the first two. That is the reason why spacecraft can use this principle to aero brake before entering orbit, and also the reason why this theory could not possibly work with the Moon, because the Moon is simply to large to fall within the given parameters of the capture equation.
Now as far as the resisting medium is concerned, Mr. See tried for many years to prove the existence of this theoretical material – unfortunately his efforts would prove fruitless.
Now that brings us to our next theory, and that is the collision theory.
The Collision Theory
The collision theory is the culmination of many ideas that were brought forth by just as many men. These men came from many different professions in life such as geologists, physicists, and astronomers, just to name a few. These theories revolve around a central idea, which basically says, that the origin of the Moon was the direct result of a giant object striking the Earth with enough force to completely destroy at least a third of the Earth’s surface. The resulting debris coagulated over a period of time to create the Moon we know today.
It is the purpose of this discussion to bring all of the previous theories together to formulate one complete idea on the origin of the Moon.
In the late 1960’s man went to the Moon. One of the goals of the manned Apollo missions was to discover if possible the origin of the Moon in order to settle once and for all – the controversy over exactly which creation theory was correct.
Discrepancies and Support in the Theories
However – if that could not be proven, then the goal was to come up with a new one. After the lunar landings it looked as if all three theories were terribly in error with the exception of the collision theory.
The first problem with the fission theory was how in the heck the Earth could have been spinning fast enough to throw off enough material to form the Moon. The second problem was why did the chemical composition of the Earth and the Moon not match? This was interesting, and chemical similarities are certainly an issue.
With the collision theory however – evidence surrounding the collision event does hold merit when you consider that the samples provided by Apollo missions do show a mixture of similarities in the chemical properties that seem to reflect that although they are similar; there are also dissimilarities, both of these examples would be favorable to the theory, if these samples were indeed those of the Moon and the proposed impacter.
The problem with the capture theory is that the discovery of past lava oceans combined with data on the Moons atmospheric chemical make up just do not coincide.
The two main problems with the co-accretion theory was the fact that – first not only did similarities in the chemical nature of the Moon not match those of Earths But second the presence of the lava oceans meant that the Moon would have had to form in a much shorter time span than was allowed by the theory.
Reginald Daly
One man who set out to address these problems was a geologist by the name of Reginald Daly, who for many years had an idea floating around in his head that the craters on the Moon were not of a volcanic nature. Daly believed that these craters were the direct result of impacts to the lunar surface. These impacts were due to multiple strikes by meteors of unknown origin. Later Daly would write that he believed that these meteors were the remains of a large collision with the Earth by an outside object. He later regretted the release of his beliefs because of the ridicule he endured from his colleagues.
Immanual Velikovsky and Joshua’s Long Day
In 1950, a Russian by the name of Immanuel Velikovsky entered the scene. He had the idea that certain events described in the bible – were not just stories – but the depictions of actual events in mans past. It was these stories – such as the telling of Joshua’s Long Day – where the Sun and the Moon were said to have stood still in the sky. It was these stories along with others – such as the one describing the planet Venus appearing like a comet in the sky for several nights. These theories fostered Velikovsky’s idea that 3,500 years ago the planet Venus had once been a moon of Jupiter, and it had some how become detached (implied impact) by some unexplained event that caused Venus to pass close enough to the Earth – to cause the Earth to momentarily stop revolving.
Then Velikovsky further stated that this was the reason the Sun and Moon seemed to stop in the sky causing “Joshua’s Long Day”. He also surmised that this event could very well have been the precursor of the amazing things that occurred during the supposed Exodus of the Israelites from Egypt. Now before Velikovskys’ theory could hold any water so to speak, he would have to prove beyond the shadow of a doubt how the planet Venus could have stayed in orbit around Jupiter for so many millions of years to one day just suddenly fly off into space, then wind up as the second planet from the Sun – which he never did.
Now, it seems to me that Valikovsky was another one of those people who wanted to make assumptions with no physical evidence to back it up. Now that brings us to a man by the name of William Hartman.
William Hartman and the Aitken Basin
In the early 60’s one of the biggest proponents of the collision theory began making some impacts of his own within the scientific community. His name was William Hartman. Mr. Hartman was employed by NASA to construct a rather large globe of the Moon. On this globe he would apply the spacecraft images taken by the previous unmanned missions to the Moon. While applying these images to the globe Mr. Hartman began to see patterns emerge. In these patterns he saw that most of the largest mountain ranges on the Moon were around the edges of large impact craters. These mountains with the highest elevations were located near the south lunar pole. This meant to Mr. Hartman that somewhere near this area – on the far side of the Moon – there must be a very large impact basin. Well he was right; it’s called the Aitkin Basin.
The discovery of the Aitkin impact region led Mr. Hartman to further collect and study research papers that involved the formation of large planetesimals. Mr. Hartman believed that these objects were formed from an accretion disc around our Sun – that became unstable due to density fluctuations. These fluctuations caused particles large and small to become gravitationally bound. As these particles became larger they began to sweep up smaller material as the objects moved within their orbits. Through this evolution these objects began to form larger objects such as moons and planets (we see evidence of this today in the rings of Saturn).
Armed with this new evidence Mr. Hartman was able to prove why the Earth has an iron core – while the Moon hardly has any at all. It further explained why the Moon has such large lava oceans. It also explained why the Moon does not appear to have any volatile elements. It also gave a good explanation as to why the rocks brought back by the astronauts, were similar to the Earth in so many respects. Then – best of all – this theory tied together all of the previous theories.
The Prevailing Theory
With all these theories brought together – including modern data – the prevailing theory is that the Earth was struck by a Mars sized object. After the initial impact the Earth was pretty well devastated with a very large chunk taken out of it (which some people believe to be the Pacific Basin). The resulting debris field orbiting the Earth was a mixture of the impacter combined with the resulting debris that was excavated from the Earth. As the Earth rotated in it’s now off balance kind of way. The majority of the mass that remained of the impacter debris – moved just ahead of the remaining debris field comprised of what was extracted from the Earth.
The gravitational torque of this off balanced Earth causes the debris field to be thrown by centrifugal force into an ever increasing higher orbit. As the Earth continues to revolve this expanding debris field begins to look like a spiral arm surrounding what’s left of the Earth. Part of this spiral arm crashes back into the Earth as a secondary impact. This secondary impact throws even more liquid debris into orbit. The result of course is that these secondary impacts thrust the already existing debris into an even higher orbit.
Now with two moons worth of debris floating in orbit around the Earth, the resulting accretion ring begins to coagulate into spiral arms again. The further coagulation of this debris by mutual gravitational attraction, later groups into a larger and larger planetesimal orb. This ever increasing orb eventually becomes our present day Moon. I know – and the million dollar question is – if we were struck by a Mars size object – then where is the hole? Well guess what folks there is no hole. The Earth was so devastated by the collision, and the resulting secondary collisions brought about by in falling debris. That the Earth reformed itself into a new sphere (well kind of a sphere, it is egg shaped after all).
Closing Remarks
All of these theories are quite thought provoking to say the least, but in essence they are all still theories, and with no positive proof otherwise, it is assumed they will stay that away, until further Moon missions planned in the near future should either confirm or deny the most rescent ideas concerning the origin of the Moon. One thing is for certain though, if it were not for the imagination and certainly a degree of personal insight provided by these aforementioned men, our knowledge of the Moon that we possess today, would certainly have been placed on the back burner long ago, leaving us with only a vision of our sister planet shrouded in mysteries that probably would have never seen the light of truth.
