Claudius Ptolemy

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Claudius Ptolemy

• by Tihomir Kostadinov
• GEOG 200B
• January 14, 2003

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Biography

• Highly uncertain we dont know much about his
  personal life.
• Lived and worked in Alexandria, Egypt.
• Born ca 85 AD
• Died ca 165 AD

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Biography

• Greek astronomer, mathematician and geographer.
• Name a mixture of Greek Egyptian Ptolemy and
  Latin Claudius.
• His teacher was probably Theon of Smyrna, a
  mathematician.

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Biography

• His work was extremely influential and defining
  fundamental principles for more than a millennium
  in the Western World.
• Most influence in astronomy and geography.
• Work in astronomy not refuted until Nicolaus
  Copernicus (1473-1573) proposed the heliocentric
  model, which was actually less precise (without
  Keplers laws)!!!
• Work in geography said to have influenced
  Columbus in his westward explorations.

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Major works/publications

• Three major books
• Almagest (Mathematical Syntaxis) - astronomy,
  trigonometry, mathematics.
• The Geography maps, geography.
• Tetrabiblos - on astrology.

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Almagest

• 13 book treatment on astronomy.
• Laid foundations of modern trigonometry.
• Knew the Earth was a sphere.
• Geocentric UNIVERSE view uses circular motions
  on several superimposed levels to explain
  planetary movements. This geocentric view was not
  improved until Copernicuss heliocentric model
  was AUGMENTED with Keplers laws!!!
• 48 constellations (over a thousand stars) catalog
  with coordinates. Names of constellations still
  used today. Ecliptic equatorial coordinates used
  with systematic and other errors.

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Almagest Geocentric View

• Used three geometric constructs (eccentric,
  epicycle, equant) to explain planetary motions,
  especially the retrograde motion (explained by
  the epicycles).
• Classic example of how an empirical model in
  science can persist and explain phenomena while
  being inherently WRONG.

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The Geography

• Influential, founding work in geography and
  cartography. Remained the principal work until
  the 1500s.
• Based on the Earth being a sphere.
• His maps are the first known projection of the
  sphere onto a plane.

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The Geography

• Coordinates on maps are degrees of latitude,
  referenced to the Equator, and degrees of
  longitude, referenced to some point westward of
  the most western point.
• The work is basically what we call an ATLAS
  today. Based around the maps.
• Only the index of the maps has remained the
  actual maps have disappeared.
• List of places, coordinates, neighboring places,
  and short descriptions sometimes.

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References/Sources Used

• http//www-gap.dcs.st-and.ac.uk/history/Mathemati
  cians/Ptolemy.html
• http//www.ku.edu/history/index/europe/ancient_rom
  e/E/Gazetteer/Periods/Roman/.Texts/Ptolemy/home.ht
  ml
• http//www.seds.org/billa/psc/theman.html
• http//galileo.imss.firenze.it/museo/a/esistea.htm
  l
• http//www.hao.ucar.edu/public/education/sp/images
  /ptolemy.html
• http//es.rice.edu/ES/humsoc/Galileo/Things/ptolem
  aic_system.html
• http//ce.eng.usf.edu/pharos/alexandria/gallery/ga
  te.jpg
• http//www.culture.gr/2/21/218/218ae/00/l5-20.html
  
• Special THANKS to Google, Inc. (www.google.com)