Analysis Final Page
Caitlyn Scott
English 302-N03
How the Moon Influences the Earth
This graphic is used with permission from NASA. http://commons.wikimedia.org/wiki/Image:Moon_Earth_Comparison.png.
The moon has always been a fascinating object in the world of man that has always seemed just out of reach. It is the mysterious disk that is suspended above the heads of millions of people around the world. It has been seen as a God and as a sense of romance that has mystified the human species for centuries, and will continue to for many more centuries to come. Though just out of reach, the moon has more influences on the planet Earth than just a subject for superstition and poetry. The affects that the moon has on the Earth are countless and vary in extremes. The most commonly known influence on the Earth is the tidal wave system that flows almost flawlessly around the planet. The moon is what controls the high and low tides that children play in during their vacations to the beach. The moon also affects the Earth on an even greater scale. The moon’s gravitational pull combined with the Earth’s gravitational pull has a major influence upon how fast the Earth rotates. The moon and the Earth have a very unique and intense relationship that has been there from the beginning.
Still today, scientists have multiple theories on how the moon was made. One theory is that the moon was formed from the thin layering crust of the earth. In other words, the moon was formed from the earth itself. However, there is another theory that is gaining a lot of support recently. This theory is that the moon and the earth were separate bodies in space. At some point in history, these two bodies collided with one another. In the aftermath of this collision, the earth became smaller than it was, and the moon was almost destroyed, but collected space debris as it orbited the Earth. Which ever theory is accepted, there is one thing that was known for sure. The moon was a lot closer to the Earth when it started its systematic orbit. As a result, the months and days were much shorter. When the moon was 11,000 miles away from the earth, the month was only six and a half hours long. This means that the earth’s “day” was about the same as well. Also, the gravitational pull coming from both bodies were much more severe. As a result, the axial rotation of both the moon and the earth were slowed down and the moon was pushed farther away from the earth. As the moon slowly retreated away from the earth, the “days” on earth elongated and the gravitational pull became less and less.
In those early days of the moon and the earth, the gravitational pull was extreme. The tidal patterns are the direct result of the moon’s gravitational pull on the planet earth, which means that the tidal pull was even more obvious and intense than it is now. Imagine the planet has having a liquid envelope. In reality, this is not true because of the continents that stand in the way of the tides and currents of the ocean. However, it is easier to picture the moon’s affects on the earth’s tides if the earth is seen as having a liquid envelope. The moon’s orbit plays a big part in how the tides are formed. The moon orbits the earth in an elliptical motion. This means that the moon is closer to the earth at certain times and farther away from the earth. When the moon is closer to the earth, the gravitational pull is greater. Because liquid is easy to manipulate, the liquid envelope is pulled towards the moon. This pull creates a “squeeze” on the envelope. This motion causes the middle of the envelope, which is not close to the moon to become smaller. When the bulge of the envelope is closer to the moon, it creates higher tides because there is more water on those sides. At the same time, the condensed sides of the envelope have less water and are experiencing low tides. Of course, the planet does not have constant high tides on two sides of the earth and constant low tides on the other sides. This is because the earth rotates, as does the moon. However, the earth rotates faster than the moon does. This results in two tidal patterns a day, every six hours. The sun does have an impact as well. When the sun and the moon are exhibiting gravitational forces at the same time, during a full or new moon, the high tides are much higher and the low tides are much lower. Though the tidal pattern is one of the more obvious influences of the moon, there is one impact that is on an even bigger scale that normally goes unnoticed.
One of the major influences that the moon has on the earth is its rotation. The moon’s gravitational pull combined with the tides, slows the earth’s rotation down by a considerable amount. The rotation of the Earth is slowed down by the friction of the tides on the ocean bottom, which is controlled by the moon. As the friction builds up, the earth slows just a little. A good example of this is if a globe is spun and a pencil is held just barely touching the globe. Eventually the globe will slow to a stop. The rate of the earth slows down 0.00000002 seconds per rotation. Though this might seem like a rather small number, eventually over time, the fractions of a second add up. In fact, the day is extended by fourteen seconds every century. As time continues on, the days on earth will continue to grow longer and longer. Also, as stated before, the moon was much closer to the earth. The laws of physics shows that an object using centripetal force will continue to be pulled farther away from the object it is orbiting. The same is true for the moon. As it continues to orbit the earth, the distance between the two bodies is becoming greater and greater. The moon moves one-tenth of an inch away from the earth every time it completes an orbit. In three or four billion years from now, the moon will be twice as far away. It will continue to move further away until the gravitational pull does not exhibit any more force upon it and it will no longer be orbiting the earth.
Eventually the earth will no longer have a heavenly disk floating in its night skies. The results of no longer having the moon could have serious impact. The tides will no longer flow in the same pattern as they do now. Also, the days could be twenty-four hours long, or longer. The other influences could be even more sever and intense. There are hundreds of theories about how the moon affects the earth and the inhabitants on it. It is said that earthquakes and volcanoes are triggered based off the moon’s activity. If there is no moon, then maybe earthquakes will not happen or volcanoes will not erupt. Time can only tell what is in store for the Earth as the moon influence and continues separate itself.
Bibliography:
Firsoff, V. A. Strange World of The Moon. Basic Books: New York. 1959.
Gamow, George. The Moon. Abelard-Schuman: London. 1959.
Lapedes, Daniel N. McGraw-Hill Encyclopedia of the Geological Sciences. McGraw-Hill Book Co: New York. 1978.
Moore, Patrick. A Guide to the Moon. W. W. Norton and Co: New York. 1953.