Sandivogius of Czechel

Sandivogius of Czechel (Polish: Sędziwój z Czechła; c. 1410– 1476)^[1] was a Polish astronomer and cartographer. He was a professor and Stobner Chair at the Kraków Academy. He is known for providing a precise orbit of the Moon by introducing an additional epycicle in the geocentric model.

Life

Probably born in Czechel in the Kingdom of Poland.

He enrolled Kraków Academy in 1423.^[2] After graduating, he taught astronomy there from 1429 to 1431,^[3] he held the special astronomy Stobner Chair (named after medieval scholar Nicholas Stobner).^[2][4] He worked on revising the Alfonsine tables, that were considered inaccurate by the academy.^[4]

In 1430, he wrote a commentary to Gerard of Cremona's Theorica Planetarium from the 13th century.^[3] In his commentary, he proposed to use two epicycles to correct the orbit of the Moon in the geocentric model.^[3] A similar model was devised by another Kraków Academy professor Albert Brudzewski, half a century later. Their ideas were later expanded by Nicolaus Copernicus for other planets.^[3] This correction explained why the Moon always shows the same side to Earth.^[5]

Sandivogious also taught optics, based on the ideas of John Peckham.^[6] He wrote a popular a commentary to Peckham's Perspective communis.^[7] Sandivogius was a perspectivist, he aligned himself with Ibn al-Haytham and Vitello.^[1][8]

In 1431, Sandivogius left Cracow. He kept correspondence with his friend and historian Jan Długosz, who kept him in close contact with the academy.^[4][9]

In 1440, he wrote Chronica Polonorum, also known as the Code de Sędziwoj, presenting a detailed description of the geography and administrative division of Poland.^[9] Between 1443 and 1444 he studied in the College of Navarre in Paris, where he offered a copy of his Code.^[9] It contains one of the remaining transcripts of the Gesta principum Polonorum.^[10]

He also wrote Algorismus minutiarium and Algorismus proportionum.^[2]