Andalusian Astronomy in the Eleventh Century Julio Samsó
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INFERENCE / Vol. 5, No. 3 Ibn al-Zarqālluh Andalusian Astronomy in the Eleventh Century Julio Samsó stronomy was first cultivated in Al-Andalus, adapted the coordinates of al-Khwārizmī’s Sindhind tables the part of the Iberian Peninsula under Islamic to Córdoba. He also studied Ptolemy’s Almagest, as well as rule, during the early ninth century. This was the Ptolemaic tables compiled by al-Battānī (c. 858–929). Amainly due to the fact that astronomy was necessary for Maslama was particularly interested in stereographic the practice of astrology. The Muslim rulers relied on the projection, as used in the making of the astrolabe and predictive powers of a team of astrologers to provide them similar instruments, and improved Ptolemy’s Planisphe- with useful information for decision-making. A group rium, the classical work in which this type of projection of poet-astrologers who served the courts of the emirs was described. Two of his disciples, Ibn al-Ṣaffār and al-Ḥakam I (r. 796–822) and his son ʽAbd al-Raḥmān II (r. Ibn al-Samḥ, applied his findings in treatises on the con- 822–852) are well attested in historical sources. The histo- struction and use of the astrolabe. These works were rian Ibn Ḥayyān recorded their names in his al-Muqtabis fī introduced in the Latin world through two compilations, tārīẖ al-Andalus. A chapter titled “Anecdotes of the Astrol- De compositione and De operatione astrolabii, made during ogers with the Emir ʽAbd al-Raḥmān II,” describes an the twelfth and thirteenth centuries.1 Through these com- attempt by the sovereign to test the accuracy of the predic- pilations, Maslama’s influence can be seen in treatises on tions made by his astrologers. It is clear from this account the astrolabe written during the thirteenth and fourteenth that ʽAbd al-Raḥmān II and the members of his court were centuries: one in Castilian by Alfonso X, another in French greatly interested in both astrology and astronomy. The by Pèlerin de Prusse, and a third in English by Geoffrey emir himself is credited with the ability to calculate plan- Chaucer. etary positions, and a musician like Ziryāb is presented as Orthodoxy returned to Al-Andalus under the lead- having a deep knowledge of both disciplines. Ibn Ḥayyān ership of al-Manṣūr ibn Abī ʽĀmir (981–1002), prime also sheds light on the books brought to Córdoba from minister for the child emir Hishām II, who was too young Baghdad by the astrologer ʽAbbās b. Nāṣiḥ (fl. ca. 800–850). to rule. Under the caliphate of Hishām’s father, al-Ḥakam Included is a list of what are presumably astronomical II (961–976), Al-Andalus had basked in one of the most tables—known as zījes in Arabic—titled al-Zīj, al-Qānūn, accomplished periods of its cultural history. Al-Manṣūr al-Sindhind, and al-Arkand. The reference to al-Zīj is too destroyed this legacy, ordering selective manuscripts from general for the purposes of identification, but Al-Qānūn the great library of al-Ḥakam II to be burned, including probably refers to Ptolemy’s Handy Tables. Al-Sindhind books on astrology and astronomy. Soothsayers and astrol- is likely the Indo-Iranian zīj compiled by al-Khwārizmī ogers were arrested, tortured, and executed for predicting in Baghdad during the first half of the ninth century; its the end of al-Manṣūr’s regime. Such predictions were still use in Al-Andalus is well documented a century later. And being made long after al-Manṣūr’s death, during the period al-Arkand is another set of Indian astronomical tables, when his two sons held political power. Maslama, among introduced in Baghdad in the eighth century. others, predicted that the conjunction of Saturn and Jupi- At the time, astronomy raised suspicions in orthodox ter in 1007 would portend the overturn of the regime, that circles due to its connections with astrology, and could the state would fall into other hands, and that there would only be cultivated under the rule of open-minded author- be killings and famine. He was proved right. After the ities. It is for this reason that there is little surviving deaths of al-Manṣūr’s sons in 1008 and 1009, a period of information about astronomical and astrological practices anarchy and civil wars followed. Between 1009 and 1031, following the death of ʽAbd al-Raḥmān II in 852. It was seven different monarchs occupied the caliphate. not until a century later that astronomy seems to have In 1031, the Córdoban caliphate came to an end. Polit- been revived, reaching maturity with the important figure ical unity was lost, and the state was divided into a set of of Maslama al-Majrīṭī (d. 1007). Maslama revised and petty kingdoms. This arrangement lasted from 1031 to 1085, 1 / 7 BIOGRAPHIES a period that could be considered the golden half-century author of the Kitāb ṭabaqāt al-umam (Categories of of Andalusian science. The loss of political unity had two Nations), a world history of science containing abundant contradictory consequences. On the one hand, the number details about the development of science in Al-Andalus of patrons who fostered scientific research grew. Each sov- between the ninth and eleventh centuries.7 The Ṭabaqāt ereign was interested in having at his service physicians, reveals the astronomical sources that were available in astrologers, and poets who would enhance his glory and Toledo toward the middle of the eleventh century: Ṣāʽid importance. On the other hand, Andalusian scientists of knew the Greek classics, particularly Ptolemy’s Almagest, this period seem to have believed that an adequate scientific Geography, and Tetrabiblos, as well as Theon of Alexan- education could be obtained without the riḥla, or traditional dria’s commentary on the Almagest and the Handy Tables. journey, to the East, which completed the standard edu- References are also made to Eastern Islamic sources of cation of any young man belonging to a family who could the ninth and tenth centuries, especially al-Khwārizmī, afford it. None of the sovereigns of the petty kingdoms seem al-Ḥasan ibn al-Ṣabbāḥ, Thābit ibn Qurra, Abū Maʽshar, to have been able to afford the expense involved in receiving Ibn al-Ādamī, and al-Hamdānī. The Ṭabaqāt gives no information about, let alone buying, new publications from indication that Ṣāʽid knew of any Eastern Islamic books Eastern capitals. The result was a long period of cultural published after 950, confirming that Andalusian culture isolation. As a result, a distinctive approach to astronomy was isolated after the fall of the Córdoban Caliphate.8 developed in Al-Andalus during this period, one that dif- Ṣāʽid was himself an astronomer and a patron of astro- fered markedly from its Eastern counterpart. nomical research. The fourteenth-century astronomer Isaac Israeli, in his Yesod ha-ʽOlam, recounts that Ṣāʽid uring the eleventh century, Toledo became gathered a team of about twelve people, mostly comprising well known as a center for astronomical activity. Muslims, but also including some Jews. They consecrated This reputation was maintained in the twelfth their lives to scientific and astronomical research, while Dand thirteenth centuries by the ongoing process of trans- ā id furnished them with adequate means for their living. Ṣ ʽ lating Arabic scientific texts into Latin.2 Yaḥyā al-Ma’mūn, Israeli notes that they used instruments built and adjusted who reigned between 1044 and 1075, was a member of the by an astronomer called Ibn al-Zarqālluh. Banū Dhī l-Nūn, a Berber dynasty who ruled the kingdom of Toledo during the eleventh century. Yaḥyā’s honorary lthough he became known as Ibn al-Zarqālluh, name, al-Ma’mūn, was likely chosen to emulate an Abbasid his full name was Abū Isḥāq Ibrāhīm ibn Yaḥyā caliph with the same name, who had patronized the first al-Naqqāsh al-Tujībī.9 He had been born near program of astronomical observations undertaken in AToledo and trained as a metalsmith, becoming an instru- Baghdad and Damascus in around 830. Al-Ma’mūn spon- ment maker for Ṣāʽid, al-Ma’mūn, and, in 1048, the young sored numerous technological marvels, contributing to ʽAbbādid prince of Seville, among others.10 Ibn al-Zarqāl- Toledo’s international reputation as the city of knowledge.3 luh’s patrons in Toledo lent him the necessary literature to During his reign, the engineer Aḥmad or Muḥammad ibn teach himself astronomy. He soon assumed a prominent Khalaf al-Murādī published his Kitāb al-asrār fī natā’ij position in the group assembled by Ṣāʽid, who mentions al-afkār (Secrets of the Results of Thoughts),4 which con- him in his Ṭabaqāt as belonging to the younger Toledan tains descriptions of 18 clepsydras, or water clocks. In the generation. Israeli reports that precision instruments same period, Abū l-Qāsim b. ʽAbd al-Raḥmān, also known were used by the group, but there is otherwise little fur- as al-Zarqāl, built a clepsydra-calendar that was used to ther information about them.11 mark the date of the lunar month.5 According to a descrip- Ṣāʽid’s group had begun making observations by at least tion by the geographer al-Zuhrī (d. 1137), al-Zarqāl built the early 1050s, leading to the compilation of a set of astro- two large basins in a house outside Toledo on the banks nomical tables known as the Toledan Tables. These were of the Tagus, near the Bāb al-dabbāghīn (Door of the Tan- adapted to the coordinates of Toledo using tabular infor- ners). The basins were filled and emptied in consonance mation derived from al-Khwārizmī’s (fl. ca. 800–950) and with the lunar phases.