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Claudius Ptolemy (; Greek: Πτολεμαῖος, Ptolemaios; Latin: Claudius Ptolemaeus; c. 100 – c. 170 AD) was a Roman mathematician, astronomer, astrologer, geographer, and music theorist, who wrote about a dozen scientific treatises, three of which were of importance to later Byzantine, Islamic, and Western European science. The first is the astronomical treatise now known as the Almagest, although it was originally entitled the Mathēmatikē Syntaxis or Mathematical Treatise, and later known as The Greatest Treatise. The second is the Geography, which is a thorough discussion on maps and the geographic knowledge of the Greco-Roman world. Read more on Wikipedia

Since 2007, the English Wikipedia page of Ptolemy has received more than 4,794,965 page views. His biography is available in 115 different languages on Wikipedia (up from 109 in 2019). Ptolemy is the 4th most popular astronomer, the 4th most popular biography from Egypt and the most popular Egyptian Astronomer.

Ptolemy is most famous for his geocentric model of the universe, which he proposed in his book, "Almagest." In this model, the earth is at the center of the universe and all other celestial bodies orbit around it.

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    Historical Popularity Index (HPI)

  • 115

    Languages Editions (L)

  • 16.58

    Effective Languages (L*)

  • 3.76

    Coefficient of Variation (CV)

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Among astronomers, Ptolemy ranks 4 out of 531Before him are Galileo Galilei, Nicolaus Copernicus, and Johannes Kepler. After him are Giordano Bruno, Tycho Brahe, Anders Celsius, William Herschel, Aristarchus of Samos, Edwin Hubble, Ulugh Beg, and Hipparchus.

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Among people born in 100, Ptolemy ranks 1After him are Pope Alexander I, Joseph of Arimathea, Longinus, Dionysius the Areopagite, Thecla, James the Less, Decebalus, Pope Telesphorus, Pope Hyginus, Saint Sarah, and Pope Victor I. Among people deceased in 170, Ptolemy ranks 1After him are Apuleius, Salvius Julianus, and Junius Rusticus.

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In Egypt

Among people born in Egypt, Ptolemy ranks 4 out of 582Before him are Moses (-1393), Cleopatra (-69), and Tutankhamun (-1341). After him are Nefertiti (-1400), Akhenaten (-1400), Euclid (-350), Hypatia (350), Yasser Arafat (1929), Hatshepsut (-1507), Catherine of Alexandria (287), and Joshua (-1355).


Among astronomers born in Egypt, Ptolemy ranks 1After him are Sosigenes of Alexandria (-80) and Timocharis (-320).