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compare and contrast presentation

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on 9 June 2015

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Transcript of compare and contrast presentation

The Geocentric Theory

The geocentric model, also known as the Ptolemaic system, is a theory that was developed by the philosopher Claudius Ptolemy who lived in circa 9 to 168 A.D. It was developed to explain how the planets, the sun,and even the stars orbit around the the earth. The geocentric model has existed even before Ptolemy though, this theory has been displayed in many greek manuscripts and as early as the 4th century B.C. Plato and Aristotle were writing about the geocentric model.
The Ptolemaic system, the most well-known versions of the geocentric model, was a complex interaction of circles. Ptolemy believed that each planet orbited around a circle, which was termed an epicycle, and the epicycle orbits on a bigger circle the deferent around the Earth. The center of the deferent is not the Earth, but a point near the midpoint of the distance between Earth and the equant. The equant was Ptolemy’s solution to some of the discrepancies that the geocentric model could not explain. The equant can be defined as the point at which an epicycle’s center always seems to move at the same speed. When an epicenter was at a different point on its deferent, then the planet moved at a different speed. To further complicate matters, each planet had a different equant. A diagram of the Ptolemaic system looks like a mess of overlapping circles.
Ptolemy was an astronomer and mathematician. He believed that the Earth was the center of the Universe. The word for earth in Greek is geo, so we call this idea a "geocentric" theory. Even starting with this incorrect theory, he was able to combine what he saw of the stars' movements with mathematics, especially geometry, to predict the movements of the planets. His famous work was called the Almagesti. In order to make his predictions true, he worked out that the planets must move in epicycles, smaller circles, and the Earth itself moved along an equant. None of this was true, but it made the math work for his predictions. This flawed view of the Universe was accepted for many centuries

He is sometimes called the grandfather of science. He studied under the great philosopher Plato and later started his own school, the Lyceum at Athens. He, too, believed in a geocentric Universe and that the planets and stars were perfect spheres though Earth itself was not. He further thought that the movements of the planets and stars must be circular since they were perfect and if the motions were circular, then they could go on forever. Today, we know that none of this is the case, but Aristotle was so respected that these wrong answers were taught for a very long time. Aristotle, outside of astronomy, was a champion observer. He was one of the first to study plants, animals, and people in a scientific way, and he did believe in experimenting whenever possible and developed logical ways of thinking. This is a critical legacy for all the scientists who followed after him.
Well over a thousand years later, Nicolaus Copernicus came up with a radical way of looking at the Universe. His heliocentric system put the Sun (helio) at the center of our system. He was not the first to have this theory. Earlier starwatchers had believed the same, but it was Copernicus who brought it to the world of the Renaissance and used his own observations of the movements of the planets to back up his idea. His ideas, including the revealation that the Earth rotates on its axis, were too different for most of the scholars of his time to accept. They used only parts of his theory. Those who did study his work intact often did so in secret. They were called Copernicans.
The heliocentric model is a theory that places the Sun as the center of the universe, and the planets orbiting around it. The heliocentric model replaced geocentrism, which is the belief that the Earth is the center of the universe. The geocentric model was the prevailing theory in Ancient Greece, throughout Europe, and other parts of the world for centuries. It was not until the 16th century that the heliocentric model began to gain popularity because technology progressed enough to gain more evidence in its favor. Although heliocentrism did not gain popularity until the 1500’s, the idea had existed for centuries throughout the world.
Geocentric theory vs Heliocentric thoery
Born in Pisa, Italy approximately 100 years after Copernicus, Galileo became a brilliant student with an amazing genius for invention and observation. He had his own ideas on how motion really worked, as opposed to what Aristotle had taught, and devised a telescope that could enlarge objects up to 20 times. He was able to use this telescope to prove the truth of the Copernican system of heliocentrism. He published his observations which went against the established teaching of the Church. He was brought to trial and, although he made a confession of wrong-doing, he was still imprisoned for life. But it was too late to lock away the knowledge that Galileo shared. Other scientists, including Sir Isaac Newton and Johannes Kepler, seized its importance and were able to learn even more about the ways of the world and the heavens beyond.
Both rotate around one celestial body
Both used to try to show what orbits what in the universe
both assumed the planets orbits were spherical and epicycles
both models of the solar system
Geocentric-everything revolves around the earth
heliocentric - everything revolves around the sun
the heliocentric model were ellipses not circular orbits
In geocentric epicycles added to epicycles
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