Transcript Claudius Ptolemy - UC Santa Barbara Geography

Claudius Ptolemy
by Tihomir Kostadinov
GEOG 200B
January 14, 2003
Biography
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Highly uncertain – we
don’t know much
about his personal
life.
Lived and worked in
Alexandria, Egypt.
Born ca 85 AD
Died ca 165 AD
Biography
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Greek astronomer,
mathematician and
geographer.
Name a mixture of
Greek Egyptian
“Ptolemy” and Latin
“Claudius”.
His teacher was
probably Theon of
Smyrna, a
mathematician.
Biography
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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 Kepler’s laws)!!!
Work in geography said to have influenced
Columbus in his westward explorations.
Major works/publications
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Three major books:
 Almagest (Mathematical
Syntaxis) - astronomy,
trigonometry, mathematics.
 The Geography – maps,
geography.
 Tetrabiblos - on astrology.
Almagest
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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 Copernicus’s
heliocentric model was AUGMENTED with
Kepler’s 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.
Almagest – Geocentric View
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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.
The Geography
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Influential, founding work in geography and
cartography. Remained the principal work until
the 1500’s.
Based on the Earth being a sphere.
His maps are the first known projection of the
sphere onto a plane.
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
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http://www-gap.dcs.stand.ac.uk/~history/Mathematicians/Ptolemy.html
http://www.ku.edu/history/index/europe/ancient_rome/E/
Gazetteer/Periods/Roman/.Texts/Ptolemy/home.html
http://www.seds.org/billa/psc/theman.html
http://galileo.imss.firenze.it/museo/a/esistea.html
http://www.hao.ucar.edu/public/education/sp/images/ptol
emy.html
http://es.rice.edu/ES/humsoc/Galileo/Things/ptolemaic_s
ystem.html
http://ce.eng.usf.edu/pharos/alexandria/gallery/gate.jpg
http://www.culture.gr/2/21/218/218ae/00/l5-20.html
Special THANKS to Google, Inc. (www.google.com)