Ibn al-\v{S}\=atir, L'ach\`evement de l'enqu\^ete et la correction des fondements / Kit\=ab nih\=aya al-s\=ul f\=i tash\=ih al-'us\=ul. \'Edition, traduction et commentaire math\'ematique par Erwan Pench\`evre

TL;DR

This book presents a critical edition and translation of Ibn al-tir's medieval astronomical treatise, reconstructing physical models and offering insights into early concepts of space and planetary motion.

Contribution

It provides the first viable lunar model based on Ibn al-tir's work, reconstructs lost demonstrations, and offers a detailed mathematical and historical analysis of medieval astronomy.

Findings

First viable lunar model in terms of Moon-Earth distance

Reconstruction of physical models from lost demonstrations

Critical analysis of medieval astronomical theories

Abstract

This book is a critical edition of a treatise of astronomy by the Syrian scholar Ibn al-\v{S}\=atir (1304-1375). The Arabic text has been established on the basis of several manuscript copies, and it has been translated into French; a bilingual index is also provided. This treatise is one of the latest and one of the most elaborate medieval work on theoretical astronomy; it is famous today for having provided the first viable lunar model in terms of the distance Moon-Earth. Although demonstrations have been consigned to another manuscript which is now lost, we reconstruct the physical models in our mathematical commentary, and we attempt at a better historical understanding of the nascent concepts of space transformations, solid reference frames, trajectory, etc. Predictions of the models are to be compared to observations and to other contemporary models, as well as theoretical premises; in turn, when records of observations are missing, those have to be recalculated by modern means. Part of our commentary is devoted to the latitudinal movement of the five planets: Ibn al-\v{S}\=atir's work on this problem belongs to a tradition initiated by Ibn al-Haytham three centuries before. Ibn al-\v{S}\=atir addresses a clever criticism to the work of his predecessor Nas\=ir al-D\=in al-T\=us\=i on this problem, thus revealing a better understanding of affine rotations in space. Many other criticisms by Ibn al-\v{S}\=atir, especially to the astronomers working at Mar\=a\.ga during the 13th century, also contribute to a better knowledge of their own work.