Page 71 - Arabian Studies (V)

Mathematical Astronomy
in Medieval Yemen

David A. King

From the ninth to the fifteenth century the astronomers of the
Islamic world were pre-eminent. During these seven centuries
numerous Muslim astronomers made new observations, compiled
new tables, devised new instruments, and in general made progress
in each of the various aspects of the science which were their
concern.1 A rather small fraction of the works that they compiled
was translated into Latin and thus available to medieval Europe;
the remainder was not known outside the Islamic world. These few
Islamic works which were transmitted are now fairly well known to
historians of science, but they hardly represent the scope of the
Muslim activity in astronomy. The vast number of Islamic astrono­
mical works that were not known in medieval Europe but which do
reflect the Muslim activity in astronomy over several centuries are
known mainly through modern studies of manuscripts.2
Medieval mathematical astronomy was concerned with such
topics as the determination of the positions of the sun, moon,
planets and the fixed stars; the prediction of planetary conjunc­
tions, eclipses, and visibility of the lunar crescent; timekeeping by
the sun and stars; and the computation of horoscopes and celestial
configurations with astrological significance. The Islamic tradition
of mathematical astronomy was based on the earlier traditions of
Greek, Sasanian, and Indian astronomy, rather than the primitive
folk astronomy of the Arabian peninsula. Since only a very small
fraction of the works compiled by Muslim astronomers was known
in medieval Europe, most of the vast corpus of Islamic astronomi­
cal literature has only become known in the West during the past
150 years, as a result of the labours of orientalists working on the
manuscripts in which this heritage is in part preserved. This type of
literature includes the zij, i.e. astronomical handbooks containing
extensive tables and instruments for solving standard problems

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