Article ID: CBB755611640

THE MERCURY MODELS OF IBN AL-ŠĀṬIR AND COPERNICUS (2019)

unapi

Copernicus' complex Mercury model in De revolutionibus is virtually identical, geometrically, to Ibn al-Šāṭir's (ca. 1305 – ca. 1375). However, the model in his earlier Commentariolus is different and in many ways unworkable. This has led some to claim that the younger Copernicus did not understand his predecessor's model; others have maintained that Copernicus was working totally independently of Ibn al-Šāṭir. We argue that Copernicus did have Ibn al-Šāṭir's models but needed to modify them to conform to a “quasi-homocentricity” in the Commentariolus. This modification, and the move from a geocentric to heliocentric cosmology, was facilitated by the “heliocentric bias” of Ibn al-Šāṭir's models, in which the Earth was the actual center of mean motion, in contrast to Ptolemy and most Islamicate astronomers. We show that: 1) Ibn al-Šāṭir sought to reproduce Ptolemy's critical elongation at the trines(±120°), but changed the Ptolemaic values at 0, ±90, and 180°; 2) in the Commentariolus, Copernicus does not try to produce viable elongations for Mercury; and 3) by the time of writing De revolutionibus, Copernicus is in full control of the Mercury model and is able to faithfully reproduce Ptolemy's elongations at all critical points. We also argue that claims regarding “natural” solutions undermining transmission are belied by historical evidence., Le modèle complexe de Mercure dans le De revolutionibus de Copernic est virtuellement identique, géométriquement, à celui d'Ibn al-Šāṭir (ca. 1305 – ca. 1375). Cependant, le modèle, antérieur, du Commentariolus est différent et il fonctionne mal. Certains en ont déduit que le jeune Copernic n'avait pas compris le modèle de son pré- décesseur; d'autres ont affirmé que l'œuvre de Copernic était totallement indépendante d'Ibn al-Šāṭir. Nous soutenons que Copernic avait les modèles d'Ibn al-Šāṭir mais qu'il a dû les modifier pour les rendre “quasi-homocentriques” dans le Commentariolus. Cette modification et le passage d'une cosmologie géocentrique à une cosmologie héliocentrique étaient rendus aisés par le “biais héliocentrique” des modèles d'Ibn al-Šāṭir, pour qui la Terre était le centre effectif du mouvement moyen, contrairement à Ptolémée et à la plupart des astronomes islamiques. Nous montrons que : 1) Ibn al-Šāṭir a cherché à reproduire les élongations critiques à ±120° de l'apogée, mais il a changé les valeurs ptoléméennes à 0, ±90 et 180° ; 2) dans le Commentariolus, Copernic n'essaie pas de reproduire des élongations viables pour Mercure;et 3) au moment de la rédaction du De revolutionibus, Copernic contrôle pleinement le modèle de Mercure et il est capable de reproduire les élongations de Ptolémée aux points critiques. Nous soutenons aussi que les arguments concernant des solutions “naturelles” qui excluent la transmission sont niés par l’évidence historique.

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Authors & Contributors
Graney, Christopher M.
Goddu, André
Ragep, F. Jamil
Benson, Donald C.
Carman, Christián Carlos
Carolino, Luís Miguel
Journals
Early Science and Medicine: A Journal for the Study of Science, Technology and Medicine in the Pre-modern Period
Journal for the History of Astronomy
Journal of Astronomical History and Heritage
Archive for History of Exact Sciences
Archives Internationales d'Histoire des Sciences
History of Science
Publishers
Cambridge University Press
Brill
Bruno Mondadori
Instytut Historii Nauki Polskiej Akademii Nauk
Oxford University Press
Springer
Concepts
Heliocentrism
Astronomy
Cosmology
Geocentrism
Celestial mechanics
Copernicanism
People
Copernicus, Nicolaus
Galilei, Galileo
Brahe, Tycho
Kepler, Johannes
Ptolemy
Capuano, Francesco
Time Periods
16th century
17th century
Renaissance
15th century
Ancient
Medieval
Places
Greece
Portugal
Lisbon (Portugal)
Institutions
Jesuits (Society of Jesus)
Comments

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