Final Project

Damian C.

Legislator:  John Whitmire, Senator

The MOON: A summary of theories on its origin

Since the dawn of man, one object in the sky has always graced our eyes when night falls. The moon, Earth’s moon, has been the center of legend, accomplishment and entertainment. But the origin of the moon has never had a concrete story. The truth is, humans do not know what the origin of the moon is. In order to be able to hypothesize the origin of the moon, one must understand previous famous theories.

Legend has always been able to tell a story about the actions and origins of objects. According to a legend, the origin of the moon was from an ancient ballgame played by indigenous Latin Americans. The game is played with a rock ball and is played much like soccer. The scoring areas were circle hoops that stood vertically and were elevated 15 feet in the air. According to this legend, a game was in progress when the King to the Kingdom, who also was the best athlete all across the land, kicked the ball so hard and so far into the sky that the rock stuck in the sky and has been there ever since.

The moon represents accomplishment for the Americans who landed on the moon and have done experiments on the moon to try to scientifically understand its origin.

Finally, the moon also has an entertainment aspect to it. I remember a British cartoon called “Wallis and Grommet” which showed a man and his dog building a rocket ship to try to he go to the moon because they believed the moon was made of cheese. Many children since, including myself, have grown up believing the moon is made of cheese and that all space shuttle missions are performed to only regain more cheese.

According to the Bible, the moon was also created by God one of those six days he worked on making the world. But because no one day was set aside for the creation of the moon, the origin of the moon has been based on four different theories which have replaced each other as knowledge and science is more abundant. These theories are the capture theory, the fission theory, the double planet theory, and the giant input theory.

Capture Theory

The capture theory was the most problematic of all the theories dealing with the moon’s origin. The overall idea is that the early earth had seized a fully formed moon that had come too close to our planet. Supposedly, the moon’s gravitational force was able to seize a spherical celestial body, as it moved toward our planet and maintained it aat a monthly revolution around the earth.

This model was the most problematic theory because was highly unlikely. The only logical location for celestial bodies the size of the moon is the asteroid belt. To capture the asteroid into earth orbit, the asteroid must travel fast enough to break its current orbit around the sun, travel fast enough to break Mars’ orbit and travel at just the right speed to easily fall into the Earth orbit. The odds of something like these things happening is highly unlikely, plus asteroids do not have many common characteristics to the earth as the moon does. Lunar samples have shown that the earth and the moon have similar quantities of oxygen isotopes, suggesting a close tie between the two celestial bodies. This model fails to explain this kinship.

Fission Theory

The fission theory did not have as many problems with it as the capture hypothesis did. The hypothesis’ main idea is that in its early stages after earth finished building its core, it spun so fast that it formed a bulge at the equator. Finally, the bulge became so big that a chunk of material was thrown off in an orbit around the earth. George Darwin, Charles Darwin’s son, first proposed this idea 100 years ago and it was revolutionary. But in modern science the hypothesis sounds like science fiction.

The fission theory does explain information that has been discovered in the present. If the moon was once a sizable chunk of the earth’s equator, that would account for the earth and the moon having the same oxygen isotopes.  But, according to calculation, the earth would have had to rotate once every 25 hours to build up the necessary force to send a chunk the moon’s size into orbit. One report said that slow accumulation of dust grains in the early stages of the earth’s origin cannot account for such a spin. Moreover, if the moon was thrown off into orbit coming from the equator, the orbit would be located on or near the equator. “The inclination of the moon’s orbit is not in the equatorial plane of the earth,” quotes a report from Planetary web.

Double Planet Theory

The double planet theory presents the idea that the moon and earth were developed as separate bodies. But both bodies were developed concurrently from a cloud of gas and dust.

The theory explains why the earth and the moon are made of the same substances. But the model fails to explain the moon’s orbit. “If the moon had formed close to the earth, it would orbit the equatorial place. On the other hand, if it had formed further away, it should orbit the plane of the elliptical,” explains Jay Melosh in his article about theories of the origin of earth. Also, the hypothesis does not explain why the earth is 16 times as dense as the moon, If the two bodies were developed at the same time, from the same dust cloud, from the same area of the solar nebula, then their densities of the two should be equal. Like the capture theory, the double planet hypothesis tries to use the idea that the moon and the earth were separate unique celestial bodies so the idea of a part of the earth used to make the moon can be ignored.

The Giant Impact Theory

The giant impat theory was a theory developed at a large convention in 1984.  It is the most recent and accepted theory of them all. It states that 4.5 billion years ago,a rock collided with a young earth andwith the collision, the moon broke away from earth to form and orbit the earth. Also, when the earth was hit by the impactor, a magma ocean was formed. The molten surface underwent evaporation to “hot rock vapor.” This vapor developed the earth’s atomosphere.

The theory does not have many holes and explains many problems other theories could not. If the moon broke away from the earth, as the theory explains, then it explains the same oxygen isotopes found on both bodies.  Also, if the moon was part of the outside of earth, not the core, but outside the core region, then it explains why there is an iron depletion on the moon. But, according to some research, if the impactor was swallowed by the earth, which most scientists theorize, the mass and velocity of the impactor necessary to break off a rock, the size of the moon is astronomical. According to a study, Camp and Esposito in 1985, their models show that many moonlets are initially formed, not a single massive one. How the moonlets combined to form one moon cannot be understood by anyone who has not worked on this project for at least 10 years – including myself.

My Theory

I believe the moon evolved almost the same what the giant impact theory explains. I believe before the impactor struck earth, earth was at a young age and still in a molten state. The earth almost resembled a mud puddle.  When the impactor hit the molten earth, almost like dropping a rock in a muddle puddle, a portion of the molten earth shot up like a liquid. A segment of this traveled so fast that it disconnected from the portion shot up from the impacted. The impactor embedded with the core causing a chemical reaction, cooling portions of the molten state and allowing the rest to evaporate to form the atmosphere. Because the disconnected part of the earth had no core, it circled itself as if it had a core. Because it had no core to keep the molten rock hot and in liquid state, the remaining molten rock began to cool as it moved away from the earth. Once the moon finished cooling, it was solid rock and slowed down until for formed a constant speed orbiting the earth.

Last Updated:  09/10/01