Ptolemy

Table of Contents

References & Edit History Quick Facts & Related Topics

Images & Videos

How did Ptolemy explain retrograde motion?

Ptolemaic system

Ptolemy's Geographia

world map derived from Ptolemy's Geographia

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

Epitome of the Almagest

mathematicians of the Greco-Roman world

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

How we understood the universe throughout history

For Students

Ptolemy summary

Read Next

Galaxy clusters like Abell 2744 can act as a natural cosmic lens, magnifying light from more distant, background objects through gravity. NASA's James Webb Space Telescope may be able to detect light from the first stars in the universe if they are gravitationally lensed by such clusters. (astronomy, space exploration, galaxies)

How Fast Is the Universe Expanding?

Planet Earth and lunar moon from space

Where Did the Moon Come From?

Union Jack flag of Great Britain, united kingdom

What’s the Difference Between Great Britain and the United Kingdom?

solar eclipse, sun, moon, astronomy, space

How Do You Tell the Difference Between Total, Annular, Solar, and Lunar Eclipses?

Arrangement of the phases of the moon in total eclipse with Blood Moon

9 Celestial Omens

Discover

Hindu Holi Festival celebrations with colored water, powder and colorful flower petals thrown over celebrants at a Hindu temple in Mathura, Uttar Pradesh, India on March 24, 2021.

Holi: Festival of Colors

cloning. First cloned cat. First cloned companion animal. CC (copy cat) female domestic shorthair cat (b. Dec. 22, 2001) photo Jan. 18, 2002. Cloned at Texas A&M Univ. College of Vet. Med. & Biomedical Sciences. Reproductive cloning genetics DNA cc cat

CC, The First Cloned Cat

Baseball laying in the grass. Homepage blog 2010, arts and entertainment, history and society, sports and games athletics

10 Greatest Baseball Players of All Time

Statue of Nostradamus

Nostradamus and His Prophecies

Iraqi Army Soldiers from the 9th Mechanized Division learning to operate and maintain M1A1 Abrams Main Battle Tanks at Besmaya Combat Training Center, Baghdad, Iraq, 2011. Military training. Iraq war. U.S. Army

8 Deadliest Wars of the 21st Century

David Cameron. President Barack Obama and Prime Minister David Cameron of the United Kingdom talk during the G8 Summit at the Lough Erne Resort in Enniskillen, Northern Ireland, June 17, 2013

What’s the Difference Between a President and a Prime Minister?

Remarkable new details of Pluto's largest moon Charon are revealed in this image from New Horizons' Long Range Reconnaissance Imager (LORRI), taken late on July 13, 2015 from a distance of 289,000 miles

Why Is Pluto No Longer a Planet?

Ptolemy: Facts & Related Content

Written and fact-checked by The Information Architects of Encyclopaedia Britannica

Facts

Also Known As	Ptolemy of Alexandria • Claudius Ptolemaeus
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

Ptolemaic system

Ptolemy's Geographia

world map derived from Ptolemy's Geographia

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

Epitome of the Almagest

mathematicians of the Greco-Roman world

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

How did Ptolemy explain retrograde motion?

How we understood the universe throughout history

See All Videos and Images →

Dig Deeper: More Articles That Discuss This Topic

Hipparchus

Greek astronomer

Understanding Newton's theory of universal gravitation

Isaac Newton

English physicist and mathematician

James Gregory.

James Gregory

Scottish mathematician and astronomer

Euclid

Euclid

Greek mathematician

Eudoxus of Cnidus

Greek mathematician and astronomer

Al-Bīrūnī, Afghan commemorative stamp, 1973.

al-Bīrūnī

Persian scholar and scientist

Edmond Halley

Edmond Halley

British scientist

John Herschel

Sir John Herschel, 1st Baronet

English astronomer

Ibn al-Haytham

Arab astronomer and mathematician

Li Zhizao

Chinese mathematician and astronomer

Johann Lambert, detail of a lithograph by Gottfried Englemann, after a portrait by Pierre-Roch Vigneron

Johann Heinrich Lambert

Swiss-German scientist and philosopher

Boscovich, detail of a portrait by an unknown artist; in Dubrovnik Cloister, Croatia

Ruggero Giuseppe Boscovich

Italian astronomer and mathematician

Lacaille, detail from an engraving

Nicolas Louis de Lacaille

French astronomer

Willebrord Snell

Dutch astronomer and mathematician

Zhang Heng: seismoscope

Zhang Heng

Chinese mathematician, astronomer, and geographer

Apollonius of Perga

Greek mathematician

Pappus of Alexandria

Greek mathematician

Heron of Alexandria

Greek mathematician

Archytas of Tarentum

Greek mathematician

Hippocrates of Chios

Greek mathematician

Quiz

Equations written on blackboard

Numbers and Mathematics

Clock face of Big Ben.

Scientists and Their Inventions Quiz

Michael Faraday (L) English physicist and chemist (electromagnetism) and John Frederic Daniell (R) British chemist and meteorologist who invented the Daniell cell.

Faces of Science

Nicolaus Copernicus. Nicolas Copernicus (1473-1543) Polish astronomer. In 1543 he published, forward proof of a Heliocentric (sun centered) universe. Coloured stipple engraving published London 1802. De revolutionibus orbium coelestium libri vi.

All About Astronomy

View of the Andromeda Galaxy (Messier 31, M31).

Astronomy and Space Quiz