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 Sharh al-Tadhkira
Manuscript |
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The thirteenth century was a time of great scholars and new discoveries in science in the Muslim World. One of these scholars was Nasir
al-Din al-Tusi who was born in Tus, Khurasan (present Iran) in 1201. Tusi's influence is felt in many fields, particularly mathematics
and astronomy.
After studying translations of Ptolemy and other Greek texts he made more accurate tables of planetary movements and produced a new set of
astronomic tables. He also wrote works on astronomical instruments that included the construction and uses of the astrolabe. Tusi also
established trigonometry as a new mathematical discipline.
Tusi was a prolific writer, and this manuscript, the Sharh al-Tadhkira, is a commentary on his astronomical work al-Tadhkira fi'ilm al-hay'a
(Memoir on the science of astronomy). It was written by 16th century scholar 'Abd al- 'Ali al-Birjandi and copied in 1620 in naskhi script.
Many commentaries were written about Tusi's work and, like most, this one re-examines Tusi's ideas, offers new solutions to astronomical
problems and discusses theoretical concerns. It is an important contribution to the history of astronomy.
Tusi's astronomical works were translated into Latin and carried to Europe where they were widely consulted for many centuries.
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This diagram, taken from the manuscript, demonstrates the geometry of a total solar eclipse. The tips of the triangles above the moon and
earth represent their shadows extending into space. Tusi was able to use trigonometry to estimate the relative sizes and distances of the
moon and sun centuries before the age of spaceflight. In fact one can find diagrams in modern astronomy texts which are almost indistinguishable
from the ancient version shown here.
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