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Iranian Muslim
Philosopher
868-929
Abu
Abdallah Muhammad Ibn Jabir Ibn Sinan al-Battani al-Harrani was
born around 858 A.D. in Harran, and according to one account, in
Battan, a State of Harran. Battani was first educated by his
father Jabir Ibn San'an al-Battani, who was also a well-known
scientist. He then moved to Raqqa, situated on the bank of the
Euphrates, where he received advanced education and later on
flourished as a scholar. At the beginning of the 9th century, he
migrated to Samarra, where he worked till the end of his life in
929 A.D. He was of Sabian origin, but was himself a Muslim.
Battani
was a famous astronomer, mathematician and astrologer. He has
been held as one of the greatest astronomists of Islam. He is
responsible for a number of important discoveries in astronomy,
which was the result of a long career of 42 years of research
beginning at Raqqa when he was young. His well-known discovery
is the remarkably accurate determination of the solar year as
being 365 days, 5 hours, 46 minutes and 24 seconds, which is
very close to the latest estimates. He found that the longitude
of the sun's apogee had increased by 16° , 47' since Ptolemy.
This implied the important discovery of the motion of the solar
apsides and of a slow variation in the equation of time. He did
not believe in the trapidation of the equinoxes, although
Copernicus held it.
Al-Battani
determined with remarkable accuracy the obliquity of the
ecliptic, the length of the seasons and the true and mean orbit
of the sun.
He
proved, in sharp contrast to Ptolemy, the variation of the
apparent angular diameter of the sun and the possibility of
annular eclipses. He rectified several orbits of the moon and
the planets and propounded a new and very ingenious theory to
determine the conditions of visibility of the new moon. His
excellent observations of lunar and solar eclipses were used by
Dunthorne in 1749 to determine the secular acceleration of
motion of the moon. He also provided very neat solutions by
means of orthographic projection for some problems of spherical
trigonometry.
In
mathematics, he was the first to replace the use of Greek chords
by sines, with a clear understanding of their superiority.
He also
developed the concept of cotangent and furnished their table in
degrees.
He wrote
a number of books on astronomy and trigonometry. His most famous
book was his astronomical treatise with tables, which was
translated into Latin in the 12th century and flourished as
De scienta stellerum — De numeris stellerum et motibus. An
old translation of this is available of the Vatican. His Zij
was, in fact, more accurate than all others written by that
time.
His
treatise on astronomy was extremely influential in Europe till
the Renaissance, with translations available in several
languages. His original discoveries both in astronomy and
trigonometry were of great consequence in the development of
these sciences.
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