Great Greek Astronomers example essay topic

THE BEGINNING OF ASTRONOMY Early races believed that the earth was flat and stationary, with the sky rotating round it once a day. The early races also believed things that sound weird to us today like the Vedic priests of India believed that the earth was supported upon 12 massive pillars and during the hours of darkness the sun travelled between these pillars without hitting them. The Hindu theory sounds even more peculiar as they believed that earth stood on the back of four elephants, which in turn the elephants stood on the shell of a gigantic tortoise, the tortoise however was supported upon a serpent floating in a limitless sea. All these beliefs had mistakes in the beginning, but as more people tried to explore astronomy, their observations and records became of more value. Most likely, the first astronomers were Chinese as they adopted a year of 365 days, which enabled them to work out a calendar, and from this they were able to predict eclipses. The Chinese did not just record eclipses, they also recorded comets as so did the Egyptians, but both civilisations were puzzled to what the phenomena meant, and they probably regarded the phenomena as being part of astrology.

The early Egyptians were extremely skilful at measuring the positions of the stars as they built the Great Pyramid that lined up with the north pole of the sky. This is important as it gave a clue to how old the Pyramid was. About 600 years before Christ, came the great Greek astronomers. Thales was the first of the great Greek astronomers, he was born in about the year 624 B. C and died around about 546 B. C, as well as being a philosopher, he too studied the stars but he went further and tried to explain what he saw. Next was Aristotle who was a famous philosopher who lived from about 384 to 322 B.C. He proclaimed that the earth was not flat but a sphere, he also argued about earth being at the centre of the universe. Aristarchus who lived from 310 to 230 B. C, he concluded that the sun was bigger than the earth, and the moon smaller than the earth, he also suggested that the earth revolved around the sun.

Another great astronomer was Eratosthenes he lived from 276 to 194 B. C, Eratosthenes worked out the size of the earth he also was in charge of the great library in Alexandria, where most of the observations and records were kept, but the library was later destroyed. The last two of the great Greek astronomers were, Hipparchus who was the first to use Aristarchus' method of astronomy, he lived from 190 to 127 B.C. The other astronomer was a man named Ptolemy lived from 85-165 A.D. He produced a book which gave not only his results but also most of the astronomers that were before him, this book provided modern scholars with plenty of information about ancient science. These two men Hipparchus and Ptolemy also kept to the older theory about Earth laying in the centre of the universe, Since scientists such as Ptolemy (a Greek astronomer who thought earth was at the centre of the universe) had stated his theory, astronomy was brought to a halt. Aristarchus had hit upon the truth but had no support to whether his theory of the sun centered universe was correct, until a scientist named Nicolaus Koppernigk or better known as Copernicus appeared. Copernicus who was born in 1473 on the river Vistula, wrote a book about the sun centred solar system, he became very doubtful whether Ptolemy's system could be correct. The main trouble he saw was that it was so complicated, for the observed movements of the planets in the sky it had to be necessary to add a large number of circles or epicycles until the scheme had become clumsy and artificial.

In the science of astronomy a more simple and straight forward theory is more accurate than a large one, and Copernicus looked for some way of avoiding the complications which Ptolemy and his followers had been forced to introduce. In a way Copernicus was better of than Ptolemy; he could make better measures of the planets and their movements, and he could be sure that these measurements were not greatly in error. He finally came to the conclusion that the earth was not at the centre of the universe. If it was assumed that the sun was at the centre than many complications could be removed with ease.

Today we think of the earth being at the centre of the universe and nothing else, Copernicus knew he was taking a huge step. He was saying that the astronomy being taught in schools and in universities was entirely wrong. Even worse still he faced opposition from the Roman Catholic Church who would certainly object to the idea that our world was not of supreme importance. Copernicus himself was a priest, and though he had worked out his theory by 1533 and written it down in a book which he called De Revolutions Orbium Caelestium, he did not feel inclined to publish it. Copernicus' book which also included the movements of all the other planets was ready but remained unpublished because it was different from the Catholic Church views where he knew it was certain to arise violent criticism from the church. Many people knew of its existence and tried to make its author give it to the world.

In 1543 De Revolutions appeared, by this time Copernicus was old and an ill man and he agreed to publish it he later died within a few hours after the first copy was released. About three years later a Danish scientist, Tycho Brahe was born, he later collected astronomical data, at the age of thirteen he was sent to university, by the age of seventeen he calculated the apparent position of the planets in the sky, and found that the official tables of planetary movements were seriously wrong, and so he began making observations himself. By 1611 a young man named Johannes Kepler worked with Tycho after his death the data was passed onto Johannes Kepler. Kepler was still based on the sun-centred solar system, but about 1609 Kepler published three laws of planetary motion.

One of the greatest achievements in astronomy was the invention of the telescope which was invented in 1609. Up to this, time astronomers had to rely on their eyes. This all changed when a Dutch spectacle maker, Hans Lippershey discovered the principle of the telescope. News travelled fast, and eventually reached Galileo Galilei, who was to become the first greatest astronomer to use a telescope.

Galileo was born in 1564, at the age of seventeen he was sent to Pisa university where he studied mathematics and experimental sciences. In the year 1609, Galileo built the first telescope (what were formerly known as refractors). The refractor worked like this, the object being studied falls upon a glass lens known as an object-glass, this bent the light rays together at a point known as the focus, where the image was formed. The image is then magnified by another lens called the eyepiece.

The distance between the object-glass and the focus was known as the focal length. During the years 1609 to 1619 Galileo marked the beginning of telescopic astronomy. He made discoveries of the surface of the moon.