Al-Sufi

Full name: 
Abū al-Husayn ‘Abd al-Rahmān Al-Sūfī
Arabic name: 
أبو الحسين عبد الرحمن الصوفي
Latin name: 
Azophi
Date of birth: 
07 Dec, 903
Date of death: 
25 May, 986

Well known astronomer (b. December 7, 903 – May 25, 986). He lived at the court of Emir 'Adhud ad-Dawla in Isfahan, where he conducted his scientific research. He made astronomical observations, which allowed him to contribute several corrections to Ptolemy's star list and did his own brightness and magnitude estimates which frequently deviated from those in Ptolemy's Almagest. He identified the Large Magellanic Cloud, which is visible from Yemen, though not from Isfahan; it was not seen by Europeans until Magellan's voyage in the 16th century.

He designed a full new nomenclature of star names and constellations, relating the ancient heritage to the local knowledge of Arabic and Islamic countries in this field.

The earliest recorded observation of the Andromeda Galaxy was done by him in 964; he described it as a "small cloud". He observed that the ecliptic plane is inclined with respect to the celestial equator and more accurately calculated the length of the tropical year. He observed and described the stars, their positions, their magnitudes and their colour, setting out his results constellation by constellation. For each constellation, he provided two drawings, one from the outside of a celestial globe, and the other from the inside (as seen from the earth). Al Sufi also wrote about the astrolabe, finding numerous additional uses for it. His most famous book, translated into Latin, is Book of Fixed Stars.