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Claudius Ptolemy (Greek: Κλαύδιος Πτολεμαίος, Klaudios Ptolemy) was a Greek mathematician, geographer, astronomer, and music theorist from Alexandria. He wrote about a dozen scientific treatises, three of which became crucial for Byzantine, Islamic, and Western European science. It is estimated that he lived 100-170 AD.

APA 7: Çarıkçıoğlu, A. E. (2023, April 21). Batlamyus. PerEXP Teamworks. [Article Link]

Who is Ptolemy?

Ptolemy (Latin: Claudius Ptolemaeus, 100 AD- 170 AD) was an Egyptian astronomer, mathematician, and geographer of Greek origin who lived in Alexandria in the second century AD. His writings in various fields are representative of the culmination of Greco-Roman science, in particular the “Geocentric (Earth-centered)” model, now known as the “Ptolemaic system”.

Almost nothing is known about the life of Ptolemy except what can be deduced from his writings. His first major astronomical work, The Almagest, has completed around 150 AD and contained reports of astronomical observations made by Ptolemy a quarter of a century earlier. The size and content of his subsequent literary production indicate that he lived until 170 AD. [1]

Ptolemy as an astronomer

The book, which is currently considered his work in general (“The best” according to Arab and Greek thinkers), was named “Hē Mathēmatikē Syntax (Syntax), (Mathematical Collection)” by Ptolemy because he believed that the movements of the celestial bodies he was dealing with could be explained in mathematical terms. Its first chapters provide observational evidence for the basic cosmological framework in which Ptolemy worked.

He argued that the Earth was a fixed sphere in the center of a much larger celestial sphere, which carried the stars, planets, Sun, and Moon rotating around it at a perfectly uniform speed, thereby causing their daily rise and order. According to him, the Sun slowly followed a large circle known as the “Ecliptic (Eclipse)” against the rotation of the celestial sphere for a year (the Moon and planets moved backward similarly, so they were also known as “Wandering stars” despite the “Fixed stars” found in the ecliptic.). Almagest’s basic assumption; is that the seemingly irregular movements of the celestial bodies are various compositions of regular, uniform, circular moves.

It is difficult to determine how much of Almagest is original because almost all the previous technical astronomical literature has been lost. Ptolemy denied that Hipparchus created planetary samples. Hipparchus defended the basic elements of the solar theory. As well as some parts of the lunar theory. [2]

Although Ptolemy has made only a few incomprehensible and humiliating statements about theoretical studies during the intervening three centuries, he has undoubtedly made great strides in planet study this time. Moreover, the accuracy of Ptolemy (especially as an observer) has been debated since the time of astronomer Tycho Brahe (1546-1601). Brahe pointed out that the Solar observations that Ptolemy claimed to have made in 141 are not real, and there is strong evidence to doubt that Ptolemy independently observed more than 1,000 stars listed in the star catalog. However, Ptolemy’s mastery of mathematical analysis is the subject of debate that has been overlooked.

Ptolemy was the pioneer of geocentric cosmology, which prevailed in the Islamic world and Medieval Europe. This situation was not due to Almagest until the chapter “Hypotheseis Tōn Planōmenōn (Planetary Hypotheses)”, which was examined later. The assumption he proposed in his work is currently called the “Ptolemaic system”. The system in question assumes that there is a unified system in which each celestial body is connected to its sphere, and a set of intertwined spheres so that it extends from the Earth to the celestial sphere without gaps. The numerical tables in the Almagest (Which allowed the calculation of planetary positions and other celestial events for any given date) had a profound impact on Medieval celestial science, partly through a separate, revised version of the tables published by Ptolemy as “Procheiroi Kanones (Useful Tables)”. Ptolemy taught later astronomers how to use quantitative observations with recorded dates to revise cosmological models.

Ptolemy also tried to put astrology on a solid foundation. The four volumes of the book he wrote on astrology called “Apotelesmatika (Astrological Effects)”, which were later published, are known as “Tetrabiblos (Four Books)”. He believed that astrology was a legitimate, if not precise, science that described the physical effects of the heavens on terrestrial life. Ptolemy recognized the validity of traditional astrological teachings but revamped the details to relate the practice to an Aristotelian understanding of nature, matter, and change. Tetrabiblos; is the most alien work for those who do not accept astral travel and cosmology that results from the interaction of qualities such as “Warmth”, “Coldness”, “Wetness” and “Dryness”. [3]

Mathematics through the eyes of Ptolemy

Firstly, Ptolemy has a place in the history of mathematics because of the mathematical methods he applied to astronomical problems. His contributions to trigonometry are significant. For example, Ptolemy’s table showing the lengths of the beams in a circle is the oldest surviving example of a trigonometric function. In addition, the solution of many astronomical problems in spherical trigonometry (Probably discovered by Menelaus, half a century before him.) was used to solve many astronomical problems applied to theorems.

One of the earliest studies of Ptolemy, “Harmonica Biblia (Books on Harmony)”, explored music theory when it has the quality of a middle way between extreme empiricism (Experimentalism) and mystical arithmetic profiteering associated with Pythagoreanism. Ptolemy’s assessment of the roles of the mind and the senses in getting scientific knowledge went beyond the theory of music.

Probably towards the end of his life, Ptolemy focused on the study of visual perception in “Optica” (Optics). It is a work that survives only in a fragmentary Medieval Latin translation of an Arabic translation.

The extent to which Ptolemy subjected visual perception to experimental detection is remarkable, as it contrasts with other Greek writers on optics. For example, the Hero of Alexandria (Who died in the middle of the first century AD.) claimed that only for philosophical reasons an object and its image in a mirror should make equal angles to the mirror. In response, Ptolemy established his principle by measuring the angles of incidence and reflection for planar and curved mirrors placed on a graded disk. Although Ptolemy could not decipher the law of arrival and refraction angles (Snell’s Law), he also measured how lines of sight are refracted at the boundary between materials of different densities, such as air, water, and glass. [4]

Ptolemy’s geography

Ptolemy has gained at least as much fame as astronomy with his identity as a geographer. The “Geōgraphikē Hyphēgēsis (Geographical Guide)” provided all the knowledge and techniques needed to draw maps of the part of the world known to Ptolemy’s contemporaries. Ptolemy admitted that he did not try to collect and sift all the geographical data on which his maps were based. Instead, he attributed them to the maps and writings of Marinus of Tyre (One of the leading geographers of the first century AD) to selectively introduce more up-to-date information about the Asian and African coasts of the Indian Ocean. If Ptolemy had not preserved the essence of his cartographic works, nothing would have been known about Marinus.

The most innovative element that Ptolemy added to geography was to record longitudes and latitudes in degrees for roughly 8,000 locations on the world map, making it possible to create an exact copy of his map. That is why we have a clear and detailed view of the inhabited world known to a resident at the height of the Roman Empire, stretching from the Shetland Islands (Shetland, Scotland) in the north to the sources of the Nile in the south, from the Canary Islands in the west to China and Southeast Asia. Ptolemy’s map is severely distorted in size and direction compared to today’s maps, which is a substance of the incomplete and incorrect descriptions of the road systems and trade routes in his possession.

Ptolemy designed two different ways of drawing a grid of lines on a flat map to represent the latitude and longitude circles on the Earth. Its grid gives a visual impression of the spherical surface of the Earth and preserves the measure of distances to a limited extent. The more complex of these map projections (representation, projection), which used arcs to represent both parallels and meridians, predicted projections that would preserve their areas in subsequent periods.

Ptolemy’s geographical works were almost unknown in Europe until 1300 when Byzantine scholars began the production of many manuscript copies, many of which were illustrated with specialists’ reconstructions (reconstructions) of Ptolemy’s maps. The Italian Jacopo D’Angelo translated this work into Latin in 1406. Numerous Latin manuscripts and first editions of Ptolemy’s Guide to Geography, most of this edition with maps, testify to the deep impression this work made on its rediscovery by Renaissance humanists. [5]

Interpretation of the astrology & Ptolemy relationship

The name of Ptolemy, who sprinkled some seeds in the garden of science with good and badness, bitter and sweet, is usually referred to today by the so-called science called “Astrology”. The first approaches in new scientific fields may be “imperfect definitions” and are organized by testing their functionality in the “anvil of life”. The purpose of searching for the truth in science is a good criterion. Even if astrology was the purpose of searching for truth from Ptolemy’s point of view, we noticed that in the following centuries and especially at the beginning of the third millennium, he used some methods for this search that did not meet the criteria of modern science. Moreover, now these methods have deviated excessively from the direction of emergence. The reason behind this deviation is scientists, their lives, and their actions cannot be truly and genuinely understood. [6]


  1. DICTIONARY ENTRY Jones, A. Raymond (2023, January 13). PtolemyEncyclopedia Britannica. [Britannica]
  2. WEBSITE GelisenBeyin.Net. (n.d.). Batlamyus, Batlamyusun Hayatı, Batlamyus Kimdir? (85 – 165). GelisenBeyin.Net. [GelisenBeyin.Net]
  3. WEBSITE Çelik, Ö., Özdil, A. Ş. (2017, September 15). Kopernik Devrimi: Güneş Merkezli Evren Teorisi ve Sonrasında, Dünya’ya Bakışımız Nasıl Değişti?. Evrim Ağacı. [Evrim Ağacı]
  4. WEBSITE O’Connor, J. J., & Robertson, E. F. (1999, April). Claudius Ptolemy. Maths History. [Maths History]
  5. PDF FILE Ankara Üniversitesi. (n.d.). Batlamyus (M.S. 150). Ankara Üniversitesi. [Ankara Üniversitesi]
  6. WEBSITE Bilim, R., Kayalı, Ö. (2021, February 06). Bilimsel Düşüncenin Doğuşu: Anaksimandros. Evrim Ağacı. [Evrim Ağacı]

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