Ptolemy: Quick Facts

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Facts

Also Known As	Claudius Ptolemaeus • Ptolemy of Alexandria
Born	c.100
Died	c.170
Notable Works	“Almagest” • “Guide to Geography” • “Hypotheseis ton planomenon” • “Optica”
Subjects Of Study	Ptolemaic system • calendar • light • projection • refraction

Photos and Videos

Medieval illustration of Claudius Ptolemaeus, known as Ptolemy, wearing a crown and holding an armillary sphere, with a scroll bearing his name.

Diagram illustrating Ptolemy's equant model, showing a stationary Earth at the center with a planet moving in a small circle called an epicycle, which itself moves along a larger circle, the deferent. The equant point is marked off-center from Earth, and the positions of apogee and perigee are labeled. Small stars are scattered in the background.

Open illuminated manuscript showing a woodcut world map from Claudius Ptolemy's Cosmographia, with landmasses outlined in color and surrounded by blue seas.

Open book showing a two-page woodcut world map from Claudius Ptolemy's Cosmographia, 1482, with blue oceans, labeled continents, and windhead figures around the border.

frontispiece to Galileo's Dialogue Concerning the Two Chief World Systems, Ptolemaic & Copernican

Epitome of the Almagest

Map of the Greco-Roman world highlighting the birthplaces of notable ancient mathematicians, marked with the pi symbol and labeled with their names. Cities such as Athens, Alexandria, Syracuse, and Miletus are shown around the Mediterranean, with modern country boundaries outlined. An inset provides detail for the region of Greece and western Anatolia.

Ptolemy's map of the world, as printed at Ulm, Ger., 1482.

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