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Ptolemy
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Ptolemy was the author of several scientific treatises, three of which would be of continuing importance to later Islamic and European science. The first is the astronomical treatise that is now known as the Almagest (in Greek, Η Μεγάλη ΣÏνταξις, "The Great Treatise", originally ΜαθηματικἠΣÏνταξις, "Mathematical Treatise"). The second is the Geography, which is a thorough discussion of the geographic knowledge of the Greco-Roman world. The third is the astrological treatise known as the Tetrabiblos ("Four books") in which he attempted to adapt horoscopic astrology to the Aristotelian natural philosophy of his day.
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Ptolemy was the author of the astronomical treatise which is now known as the Almagest (although that was not its original name). In this work he formulated a geocentric model of the solar system which was to remain the generally accepted model in the Western and Arab worlds for more than 1300 years. The Almagest ... contains a star catalogue. Its list of 48 constellations is ancestral to the modern system of constellations, but unlike the modern system there were gaps between them.
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Ptolemy's map had some problems. To measure distances in degrees, you need to know the circumference of the earth. And Ptolemy's estimate of the circumference of the earth was not as good as the one Eratosthenes had made. In modern units, Ptolemy's estimate comes out to about 28800000 meters. This is much less than the correct value of 40000000 meters, so Ptolemy's maps were not very accurate.
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Ptolemy had Alexander's body brought for burial to Egypt, where it was permanently interred at the city Alexander had founded and named after himself. This could have been because of his high regard for Alexander but it is more likely that it was to gain political and religious advantage.
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Ptolemy X, on the other hand, was fighting Ptolemy IX, who controlled the country, and needed to raise the fleet that he eventually led to his death. Phoenicia was a natural place to do that, and Roman financiers in the East a natural resource to turn to. Badian proposes that Ptolemy X raised the capital to finance his fleet by using his rights to the Egyptian throne as collateral, with reversion being expressed through the will; in effect he positioned the Roman state as his guarantor.
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On the motions of the Sun, Moon, and planets, Ptolemy again extended the observations and conclusions of Hipparchus--this time to formulate his geocentric theory, which is popularly known as the Ptolemaic system. (See Ptolemy's theory of the solar system.) In the first book of the Almagest, Ptolemy describes his geocentric system and gives various arguments to prove that, in its position at the center of the universe, the Earth must be immovable. Not least, he showed that if the Earth moved, as some earlier philosophers had suggested, then certain phenomena should in consequence be observed. In particular, Ptolemy argued that since all bodies fall to the center of the universe, the Earth must be fixed there at the center, otherwise falling objects would not be seen to drop toward the center of the Earth. Again, if the Earth rotated once every 24 hours, a body thrown vertically upward should not fall back to the same place, as it was seen to do. Ptolemy was able to demonstrate... that no contrary observations had ever been obtained.
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