Ptolemy's Astronomical And Geographical Work example essay topic

Claudius Ptolemaeus who is more commonly known as Ptolemy was an Egyptian astronomer, mathematician, and geographer of Greek descent who flourished in Alexandria during the 2nd century AD. He represented a degree of achievement in several fields, particularly his model of the universe now known as the Ptolemaic System. Since there is no exact date on when Ptolemy was born, many experts believe that he was born sometime around 87 AD. Ptolemy was born in Alexandria (Southern Egypt), some claimed that he was born in Hermiou (Northern Egypt) though no evidence exists that Ptolemy lived anywhere but Alexandria. Ptolemy died most probably between 140 and 170 AD. The place of Ptolemy's death is unknown but experts believe he may have died in Alexandria.

Various sources report different years of Ptolemy's birth date and his death date, however, the first observation made by Ptolemy which was given a date exactly was on 26 March 126 while the last was 2 February 141. Very little is known about Ptolemy's personal life and education, other than that he lived and worked in Alexandria; one of the primary centers of Greek culture in late antiquity and a great center of learning at that time. Ptolemy worked in a great library. Ptolemy is known for his three scholarly works: The Almagest- which focused on astrology and geometry, the Ptolemaic System- which focused on astrology, and most importantly, Geography- which advanced geographic knowledge. Ptolemy discovered the irregularity in the moon's motion, known as evection, and made original observations regarding the motions of the planets, his place in the history of science is that of collator and expounder. He formulated and recorded the data and doctrines that were known to Alexandrian men of science.

His works on astronomy and geography were the standard textbooks until the teachings of Copernicus came to be accepted. The mathematical and astronomical systems developed by the Greeks are contained in his 13-volume work, The Almagest. He presented in his famous book problems and explanations dealing with the known heavenly bodies and their relations to the earth. The Almagest also contains other astronomical information, including a catalog of more than 1020 stars (giving their latitudes, longitudes, and magnitudes), as well as mathematical information, including a table of chords. The Ptolemaic system thus evolved represented the earth (a globe in form) as stationary in the center of the universe, with sun, moon, and stars revolving about it in circular orbits and at a uniform rate. From the center outward the elements were earth, water, air, fire, and ether.

Beyond lay zones, or heavens, each an immense sphere. The planets were assumed to revolve in small circles, called epicycles, whose centers revolved around the earth in the vast circles, or deferent's, of the spheres. The Ptolemaic System is the Greek geocentric view of the universe, and calculated the apparent motions of the planets, as they were known in his time by synthesizing and extending Hipparchus's system of epicycles and eccentric circles to explain his geocentric theory of the solar system. Ptolemy's system of geography had many errors stem from his underestimation of the earth's circumference. However, his system was in use until the 16th cent. Geography consisted of eight volumes.

The first discussed the problems of representing a spherical earth on a flat sheet of paper and provided information about map projections. The second through seventh volumes of the work were a gazetteer of sorts, as a collection of eight thousand places around the world. This gazetteer was remarkable for Ptolemy invented latitude and longitude - he was the first to place a grid system on a map and use the same grid system for the entire planet. His collection of place names and their coordinates reveals the geographic knowledge of the Roman empire in the second century. The final volume of Geography was Ptolemy's atlas featured maps that utilized his grid system and maps that placed north at the top of the map, a cartographic convention that Ptolemy created. Unfortunately, his gazetteer and maps contained a great number of errors due to the simple fact that Ptolemy was forced to rely upon the best estimates of merchant travelers.

Geography had a profound effect on the geographical understanding of the world in the Renaissance and it was fortunate that its knowledge was rediscovered to help establish geographical concepts that we almost take for granted today. Ptolemy was said to have inspired Christopher Columbus with his maps of Africa and Asia, in his westward expedition to India across the Atlantic. His maps were amazingly accurate for the time, but had Asia extending much too far east. This may have been a deciding factor in Columbus's decision to sail west for the Indies. Ptolemy is considered one of the greatest accomplished geographers in late antiquity. Not only was he an astronomer, Ptolemy was very important in the history of geography and cartography.

He was well aware the earth was a sphere. Ptolemy's is the first known projection of the sphere onto a plane. In addition he constructed several maps, including a map of the world. Ptolemy's astronomical and geographical work were enshrined in books and his mathematical theories are most valuable in the field of trigonometry; which are preserved. He wrote many books that people then and now find very useful. His writings, circulated in the original Greek and in Arabic and Latin translations, include also the Tetrabiblos, a study of astrology.

His Geography remained the principal work on the subject until the time of Columbus. His geographical understandings of the world helped establish many concepts that we use today.