Delineates the two very different traditions of astronomy in medieval Islam: legal scholars watched the crescent moon to keep the calendar, and used shadows to keep the hours and direction of prayer, while astronomers constructed elaborate theories and mathematical tables to approach ever more precision in times and directions. The articles are reproduced from their original publication in various journals, 1982-91.

In On Both Sides of the Strait of Gibraltar Julio Samsó shows that astronomical sources, written in al-Andalus, the Maghrib and the Iberian Peninsula, belong to the same tradition and emphasizes the role of al-Andalus and the Iberian Peninsula in the transmission of Islamic astronomy to medieval Europe.

It was the astronomers and mathematicians of the Islamic world who provided the theories and concepts that paved the way from the geocentric theories of Claudius Ptolemy in the second century AD to the heliocentric breakthroughs of Nicholas Copernicus and Johannes Kepler in the sixteenth and seventeenth centuries. Algebra, the Arabic numeral system, and trigonometry: all these and more originated in the Muslim East and undergirded an increasingly accurate and sophisticated understanding of the movements of the Sun, Moon, and planets. This nontechnical overview of the Islamic advances in the heavenly sciences allows the general reader to appreciate (for the first time) the absolutely crucial role that Muslim scientists played in the overall development of astronomy and astrology in the Eurasian world.

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-BÃ(R)rûnÃ(R), alas corrupted by careless copying; and a table of geographical coordinates from 15th-century Egypt.

First published as a special issue of the journal Medieval Encounters (vol. 23, 2017), this volume, edited by Josefina Rodríguez-Arribas, Charles Burnett, Silke Ackermann, and Ryan Szpiech, brings together fifteen studies on various aspects of the astrolabe in medieval cultures. The astrolabe, developed in antiquity and elaborated throughout the Middle Ages, was used for calculation, teaching, and observation, and also served astrological and medical purposes. It was the most popular and prestigious of the mathematical instruments, and was found equally among practitioners of various sciences and arts as among princes in royal courts. By considering sources and instruments from Muslim, Christian, and Jewish contexts, this volume provides state-of-the-art research on the history and use of the astrolabe throughout the Middle Ages. Contributors are Silke Ackermann, Emilia Calvo, John Davis, Laura Fernández Fernández, Miquel Forcada, Azucena Hernández, David A. King, Taro Mimura, Günther Oestmann, Josefina Rodríguez-Arribas, Sreeramula Rajeswara Sarma, Petra G. Schmidl, Giorgio Strano, Flora Vafea, and Johannes Thomann.

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.