mirrored file at http://SaturnianCosmology.Org/ For complete access to all the files of this collection see http://SaturnianCosmology.org/search.php ========================================================== [1][LINK] Ptolemy (aka Claudius Ptolemaeus, Ptolomaeus, Klaudios Ptolemaios, Ptolemeus) lived in Alexandria (in Egypt) from approx. 87 -150 AD. Very little is known about his personal life (the image above is probably purely the artist's imagination) He was an astronomer, mathemetician and geographer. He codified the Greek geocentric view of the universe, and rationalized the apparent motions of the planets as they were known in his time. [2][LINK] Ptolemy synthesized and extended Hipparchus's system of epicycles and eccentric circles to explain his geocentric theory of the solar system. Ptolemy's system involved at least 80 epicycles to explain the motions of the Sun, the Moon, and the five planets known in his time. He believed the planets and sun to orbit the Earth in the order Mercury, Venus, Sun, Mars, Jupiter, Saturn . This system became known as the Ptolemaic system. It predicts the positions of the planets accurately enough for naked-eye observations This is described in the book _Mathematical Syntaxis_ (widely called the _Almagest_), a thirteen book mathematical treatment of the phenomena of astronomy. It contains a myriad of information ranging from earth conceptions to sun, moon, and star movement as well as eclipses and a breakdown on the length of months. The Almagest also included a star catalog containing 48 constellations, using the names we still use today. In addition to his well known works in astronomy, Ptolemy was very important in the history of geography and cartography. Ptolemy of course knew that the Earth is a sphere. Ptolemy's is the first known projection of the sphere onto a plane. His [3]Geography remained the principal work on the subject until thetime of Columbus. But he had Asia extending much too far east, which may have been a factor in Columbus's decision to sail west for the Indies. The Ptolemaic explanation of the motions of the planets remained the accepted wisdom until the Polish scholar Copernicus proposed a heliocentric view in 1543. It should be noted, too, that Ptolemy's system is actually more accurate than Copernicus's. The heliocentric formulation does not improve on Ptolemy's until Kepler's Laws are also added. It is doubtful that Ptolemy actually believed in the reality of his system. He may have thought of it only as a method of calculating positions. Ptolemy also wrote _Tetrabiblos_, a work on astrology. (In those days, astrology was a reputable field of study.) [Note: There were also a number of Egyptian rulers known as Ptolemy some of whom may have been contemporaneous with the astronomer. Though he lived in Egypt, Ptolemy was a Greek.] Links * a quick bio from [4]IMSS, Firenze * nice page from [5]University of St. Andrews, Scotland * [6]Greek Astronomy, from the Vatican Exhibit; including images of Ptolemy's [7]Almagest and [8]Geography * [9]Ptolemy's Geography, from the Vatican Exhibit; including [10]Handy Tables * [11]another map from a 15th century translation of Ptolemy's Geography; ([12]another version) * [13]Ptolemy's Geography as a GIS * [14]History and Philosophy of Western Astronomy has a short section on Ptolemy and his predecessors. * [15]bibliography * [16]Ptolemy and Geography * [17]Documents of Astronomical History, including an excerpt from Almagest * [18]machine readable version of the star catalogue in the Almagest _________________________________________________________________ [19]PSC Home [20]Bill Arnett; last updated: 2000 Jun 7 References 1. file://localhost/www/sat/files/cul/img/ptolemybig.gif 2. file://localhost/www/sat/files/cul/img/spheres.gif 3. http://www.ukans.edu/history/index/europe/ancient_rome/E/Gazetteer/Periods/Roman/.Texts/Ptolemy/home*.html 4. http://galileo.imss.firenze.it/museo/b/etolome.html 5. http://www-history.mcs.st-andrews.ac.uk/history/Mathematicians/Ptolemy.html 6. http://www.ncsa.uiuc.edu/SDG/Experimental/vatican.exhibit/exhibit/d-mathematics/Greek_astro.html 7. http://www.ncsa.uiuc.edu/SDG/Experimental/vatican.exhibit/exhibit/full-images/d-mathematics/math17.gif 8. http://www.ncsa.uiuc.edu/SDG/Experimental/vatican.exhibit/exhibit/full-images/d-mathematics/math21.gif 9. http://sunsite.unc.edu/expo/vatican.exhibit/exhibit/d-mathematics/Ptolemy_geo.html 10. http://sunsite.unc.edu/expo/vatican.exhibit/exhibit/d-mathematics/images/math12a.jpg 11. http://netspot.city.unisa.edu.au/wm/map/ 12. http://portico.bl.uk/exhibitions/maps/ptolemy.html 13. http://perseus.holycross.edu/e-scapes/Lexicon/Ptolemy.html 14. http://www.bc.cc.ca.us/programs/sea/astronomy/history/histryin.htm 15. http://aleph0.clarku.edu/~djoyce/mathhist/ptolemy.html 16. http://www.utexas.edu/depts/grg/ustudent/frontiers/fall95/grumbles/grumbles.html 17. http://www.stcloud.msus.edu/~physcrse/astr106/doc.html 18. ftp://adc.gsfc.nasa.gov/pub/adc/archives/catalogs/5/5061/ 19. file://localhost/www/sat/files/cul/psc.html 20. file://localhost/www/sat/files/arnett.html