From: Thomas Hockey et al. (eds.). The Biographical Encyclopedia of Astronomers, Springer Reference. New York: Springer, 2007, p. 549

Courtesy of

Ibn al‐Aʿlam: ʿAlī ibn al‐usayn Abū al‐Qāsim al‐ʿAlawī al‐Sharīf al‐usaynī

Josep Casulleras

Diedpossibly Baghdad, (Iraq), 985

Ibn al‐Aʿlam composed a zīj (astronomical handbook with tables) that later influenced astronomy in Iraq and Iran, especially Naīr al‐Dīn al‐ūsī's īlkhānī Zīj (13th century), and in Byzantium. He was also reported to have practiced astrology under the patronage of the Būyid ruler of Baghdad ʿAud al‐Dawla (978–983) and to have cultivated musical theory. Very little is known about Ibn al‐Aʿlam's life and work. His zīj, unfortunately lost, is only known by later references in other astronomical works. One of the names given to this work, al‐Zīj al‐ʿAudī, derives from the name of his patron. It was also known as al‐Zīj al‐Sharīf, from the name of the author, and al‐Zīj al‐Baghdādī, which either refers to his place of residence or may indicate that the original tables were based on the prime meridian of Baghdad.

Ibn al‐Aʿlam's work attracted significant interest, mainly because of the observations attributed to him; the values from his zīj are reported in several sources in Arabic, Persian, and Greek. Recent analyses of the quoted planetary parameters for epoch positions, mean motions, and equations indicate that Ibn al‐Aʿlam's planetary tables were formed on the basis of a review and consolidation of earlier observations rather than by his own observations. There is, though, no information available on other materials typically found in this kind of work, such as tables for calendars, geographical coordinates, fixed stars, or trigonometric and spherical functions.

Regarding the influence of the work, Greek sources mention Ibn al‐Aʿlam under the name of Alim; there is evidence for the existence of a Byzantine version of his tables, adapted to the Byzantine calendar and, probably, to the meridian of Constantinople, made by the year 1032 and used one century later for casting a pair of horoscopes for the years 1153 and 1162. A number of Persian and Arabic sources reveal that Ibn al‐Aʿlam's tables were being used from his own time until the 14th century. In al‐Zīj al‐ākimī, the Egyptian astronomer Ibn Yūnus (circa 990) stated that Ibn al‐Aʿlam made observations with instruments constructed by him, and he took the motion of the mean Sun and the rate of precession from Ibn al‐Aʿlam's tables. The Persian astronomer Shams al‐Munajjim Muammad ibn ʿAlī al‐Wābkanawī reported in his zīj (circa 1320) that in the Zīj‐i īlkhānī, the group of astronomers working at the Marāgha Observatory under ūsī did not apply their own observations, but used the mean motions of Ibn al‐Aʿlam. Indeed, an analysis of the Zīj‐i īlkhānī shows that the underlying parameters used for the solar, lunar, and planetary tables were all taken from Ibn al‐Aʿlam and Ibn Yūnus. Finally, the Persian Zīj‐i Ashrafī, written circa 1310 by Sayf‐i Munajjim Muammad ibn Abī ʿAbd Allāh Sanjar al‐Kāmilī, preserves the values of Ibn al‐Aʿlam for the radices, the equations, and the apogees.

Selected References

Kennedy, E. S. (1956). “A Survey of Islamic Astronomical Tables.” Transactions of the American Philosophical Society, n.s., 46, pt. 2: 121–177. (Reprint, Philadelphia: American Philosophical Society, 1989.)

——— (1977). “The Astronomical Tables of Ibn al‐Aʿlam.” Journal for the History of Arabic Science 1: 13–23.

King, D. A. and J. Samsó (2001). With a contribution by B. R. Goldstein. “Astronomical Handbooks and Tables from the Islamic World (750–1900): An Interim Report.” Suhyal 2: 9–105.

Mercier, Raymond (1989). “The Parameters of the Zīj of Ibn al‐Aʿlam.” Archives internationales d'histoire des sciences 39: 22–50.

Sayılı, Aydın (1960). The Observatory in Islam. Ankara: Turkish Historical Society, pp. 107–109.

Sezgin, Fuat Geschichte des arabischen Schrifttums. Vol. 5, Mathematik (1974): 309; Vol. 6, Astronomie (1978): 215–216, 293–294. Leiden: E. J. Brill.

Tihon, Anne (1989). “Sur l'identité de l'astronome Alim.” Archives internationales d'histoire des sciences 39: 3–21. (Reprinted in Tihon, Études d'astronomie byzantine, IV. Aldershot: Variorum, 1994.)