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'ABD AL-RAHMAN AL-SUFI (AZOPHI) (903 - 986 C.E.)
'Abd al-Rahman Al-Sufi, known in the West as Azophi,
was one of the two most outstanding practical astronomers
of the Middle Ages. Al-Sufi was the first astronomer
to describe the 'nebulosity' of the nebula in Andromeda
in his book of constellations (atlas of heavens). He
named the southern group of stars al-Baqar al-Abyad
or the 'White Bull' after receiving reports from Arab
navigators in the Malay Archipelago. We now know this
group of stars as Nubecula Major (the greater Magellanic
Cloud).
Al-Sufi prepared charts of the heavens from his own
observations and carefully adjudged their magnitudes.
His book 'Kitab al-Kawatib al-Thabit al-Musawwar' was
a masterpiece on stellar astronomy. It is available
in the original Arabic and in French translation by
Schjellerup. Kitab al-Kawatib is considered important
even now for the study of proper motions and long period
variables. In it he included theta Eridani among the
13 brightest stars then known. Ulugh Beg, the grandson
of Timur (Tamerlane), in 1437 found it to be of the
first magnitude in his list of fixed stars. Edmond Halley
in his voyage to St. Helena at the beginning of the
Eighteenth century saw it as a star of the third magnitude.
Al-Sufi stated that the color of the Sirms (alpha canes
majoris) does not change, which is confirmed by later
observations. Ironically, Seneca reported to have observed
it red in Rome, Ptolemy in Alexandria reddish, and Schmidt
(1841) in Athens had observed it white after finding
yellow for a few days. It is presumed that these contradicting
observations must have been due to local variations
of weather. Al-Sufi observed the color of Algol, beta
Persei, (Arabic Al-Ghoul), to be ruddy.
Beer and Madler in their famous work Der Mond (1837)
mention a surface feature of the moon after As-Sufi
(Azophi). It is a mountainous ring twenty-six miles
in diameter in the ninth section of the lunar map. Al-Sufi's
influence in astronomy was substantial. It is reported
that the Buwayh Sultan, Sharaf-al-Dawlah, became interested
in astronomy because of Al-Suphi's influence.
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