Klavdiy Ptolemey Ancient Greek scientist. Country: Greece

1. Biography of Claudius Ptolemy
2. Life and Works
3. Contributions
4. Chronology and Optics

Biography of Claudius Ptolemy

Claudius Ptolemy (2nd century AD), an ancient Greek scientist, is known for developing the so-called geocentric model of the universe. According to this model, all visible movements of celestial bodies were explained by their (often very complex) motion around the stationary Earth.

Life and Works

Very little is known about Ptolemy's life. It is understood that he spent most of his life in Alexandria, where he conducted astronomical observations from 127 to 151. It is believed that he passed away around 168. Ptolemy's main astronomical work is "The Great Mathematical Construction of Astronomy in 13 Books," known by its Arabic name "Almagest." Until the publication of Nicolaus Copernicus' book "On the Revolutions of the Celestial Spheres," Almagest remained the unmatched reference for presenting the entirety of astronomical knowledge.

Contributions

Ptolemy's work had significant practical importance for navigation and the determination of geographical coordinates. In Almagest, for the first time, the laws of the apparent movements of celestial bodies were established to such an extent that it became possible to precalculate their positions.

Ptolemy's other well-known work is "Geography" (8 books), which gained great popularity. This comprehensive and well-systematized summary of ancient geographical knowledge had 42 editions published between 1475 and 1600. Ptolemy made significant contributions to the development and use of cartographic projection theory. He provided coordinates for 8000 locations, covering Scandinavia to the Nile's source in terms of latitude and the Atlantic Ocean to Indochina in terms of longitude. However, these coordinates were primarily based on information from merchants and travelers, rather than astronomical determinations. The treatise is accompanied by one general and 26 special maps of the Earth's surface.

Chronology and Optics

Ptolemy also compiled the "Chronological Canon of Kings," which became an important source for chronology as astronomical observations in ancient times were dated by the reigns of kings.

Although Ptolemy's five-volume treatise on optics was considered lost, a nearly complete Latin translation from Arabic was discovered in 1801. Of particular interest in the treatise are Ptolemy's developed theories on mirrors, tables of angles of refraction when light passes from air to water and glass, as well as the theory and table of astronomical refraction.