Studies In Medieval Astronomy And Optics

In this selection of studies, J.L. Mancha explores aspects of the development of medieval optics and astronomy, including some medieval antecedents of the work of early modern astronomers. The articles deal with Latin, Hebrew and Arabic texts, and the process of translation and transmission of knowledge, and focus on three main themes. First, the theory and astronomical use of the pinhole camera in the 12th and 13th centuries; the texts edited here contain a solution to the problem of the formation of images cast by light through triangular apertures, equivalent to Kepler's, a description of the correct procedure for measuring solar apparent diameters using finite apertures, and a derivation of the Sun's eccentricity from its apparent diameters at apogee and perigee. Second, the characteristics of the Latin and Provençal versions of Levi ben Gerson's astronomical work, composed in collaboration with the author, as well as his tables and canons for finding syzygies and the mathematical methods used in the derivation of parameters. Third, different aspects of the survival of homocentric astronomy in the Middle Ages, especially al-Bitruji's model for trepidation and the technique for calculating the hippopede resulting from Eudoxan couples.

This volume of 12 studies, mainly published during the past 15 years, begins with an overview of the Islamic astronomy covering not only sophisticated mathematical astronomy and instrumentation but also simple folk astronomy, and the ways in which astronomy was used in the service of religion. It continues with discussions of the importance of Islamic instruments and scientific manuscript illustrations. Three studies deal with the regional schools that developed in Islamic astronomy, in this case, Egypt and the Maghrib. Another focuses on a curious astrological table for calculating the length of life of any individual. The notion of the world centred on the sacred Kaaba in Mecca inspired both astronomers and proponents of folk astronomy to propose methods for finding the qibla, or sacred direction towards the Kaaba; their activities are surveyed here. The interaction between the mathematical and folk traditions in astronomy is then illustrated by an 11th-century text on the qibla in Transoxania. The last three studies deal with an account of the geodetic measurements sponsored by the Caliph al-Ma'mûn in the 9th century; a world-map in the tradition of the 11th-century polymath al-Bîrûnî, alas corrupted by careless copying; and a table of geographical coordinates from 15th-century Egypt.

This volume comprises nine articles on Islamic astronomy published since 1989 by Benno van Dalen. Van Dalen was the first historian of Islamic astronomy who made full use of the new possibilities of computers in the early 1990s. He implemented various statistical and numerical methods that can be used to determine the mathematical properties of medieval astronomical tables, and utilized these to obtain entirely new, until then unattainable historical results concerning the interdependence of individual tables and hence of entire astronomical works. His programmes for analysing tables, making sexagesimal calculations and converting calendar dates continue to be widely used. The five articles in the first part of this collection explain the principles of a range of statistical methods for determining unknown parameter values underlying astronomical tables and present extensive step-by-step examples for their use. The four articles in the second part provide extensive studies of materials in unpublished primary sources on Islamic astronomy that heavily depend on these methods. The volume is completed with a detailed index.

An hommage to Gad Freudenthal, this volume offers studies on the history of science and on the role of science in medieval and early-modern Jewish cultures, investigating various aspects of processes of knowledge transfer and scientific cross-cultural contacts,

This is a survey of the numerous astronomical tables compiled in the late Middle Ages, which represent a major intellectual enterprise. Such tables were often the best way available at the time for transmitting precise information to the reader.

These articles discuss the appropriation of Greek science by scholars in the world of medieval Islam. After presenting the historiography of this process, the volume focuses on Ibn al-Haytham, one of the most influential figures of the 11th century, and on his contribution to the science of optics and the psychology of vision. The work then analyzes how Greek thought was developed in the Islamic world, based on studies of Euclid's geomotry and critiques of Ptolemaic astronomy. Finally, some articles consider the history of logic - Aristotelian syllogism and Avicenna's views on the subject matter of logic.

In Measuring Shadows, Raz Chen-Morris demonstrates that a close study of Kepler’s Optics is essential to understanding his astronomical work and his scientific epistemology. He explores Kepler’s radical break from scientific and epistemological traditions and shows how the seventeenth-century astronomer posited new ways to view scientific truth and knowledge. Chen-Morris reveals how Kepler’s ideas about the formation of images on the retina and the geometrics of the camera obscura, as well as his astronomical observations, advanced the argument that physical reality could only be described through artificially produced shadows, reflections, and refractions. Breaking from medieval and Renaissance traditions that insisted upon direct sensory perception, Kepler advocated for instruments as mediators between the eye and physical reality, and for mathematical language to describe motion. It was only through this kind of knowledge, he argued, that observation could produce certainty about the heavens. Not only was this conception of visibility crucial to advancing the early modern understanding of vision and the retina, but it affected how people during that period approached and understood the world around them.