zij

A zij ( fa, زيج, zīj) is an Islamic astronomical book that tabulates parameters used for astronomical calculations of the positions of the Sun, Moon, stars, and planets.

Etymology

The name ''zij'' is derived from the Middle Persian term ''zih'' or ''zīg'', meaning cord. The term is believed to refer to the arrangement of threads in weaving, which was transferred to the arrangement of rows and columns in tabulated data. In addition to the term ''zīj'', some were called by the name ''qānūn'', derived from the equivalent Greek word, .

Historically significant zijes

The Zij-i Sultani published by Ulugh Beg in 1438/9, was utilized as a reference zij throughout Islam during the early modern era. Omar Khayyam's Zij-i Malik Shahi was updated throughout the modern era under various sultanates. Zijes were updated by different empires to suit the interests of that empire, such as the simplified version of Zij-i Sultani by the Mughal Empire.

History

Some of the early ''zījes'' tabulated data from Indian planetary theory (known as the Sindhind) and from pre-Islamic Sassanid Persian models, but most ''zījes'' presented data based on the Ptolemaic model. A small number of the ''zījes'' adopted their computations reflecting original observations but most only adopted their tables to reflect the use of a different calendar or geographic longitude as the basis for computations. Since most ''zījes'' generally followed earlier theory, their principal contributions reflected improved trigonometrical, computational and observational techniques.

The content of ''zījes'' were initially based on that of the ''Handy Tables'' (known in Arabic as ''al-Qānūn'') by Ptolemy, the ''Zij-i Shah'' compiled in Sassanid Persia, and the Indian Siddhantas by Aryabhata and Brahmagupta. Muslim ''zijes'', however, were more extensive, and typically included materials on chronology, geographical latitudes and longitudes, star tables, trigonometrical functions, functions in spherical astronomy, the equation of time, planetary motions, computation of eclipses, tables for first visibility of the lunar crescent, astronomical and/or astrological computations, and instructions for astronomical calculations using epicyclic geocentric models. Some ''zījes'' go beyond this traditional content to explain or prove the theory or report the observations from which the tables were computed. Due to religious conflicts with astrology, many astronomers attempted to separate themselves from astrology, specifically intending for their ''zījes'' not to be used for astrological computations. However, many ''zījes'' were used this way regardless, such as Ibn al-Shatir's ''al-Zij al-jadīd''.

Over 200 different ''zījes'' have been identified that were produced by Islamic astronomers during the period from the eighth to the fifteenth centuries. The greatest centers of production of ''zījes'' were Baghdad under the Abbasid caliphs in the 9th century, the Maragheh observatory in the 13th century, the Samarkand observatory in the 15th century, and the Constantinople Observatory of Taqi ad-Din in the 16th century. Nearly 100 more ''zijes'' were also produced in India between the 16th and 18th centuries. One of the most famous Indian ''zijes'' was the ''Zij-i Muhammad Shahi'', compiled at Jai Singh II of Amber's Jantar Mantar observatories. It is notable for employing the use of telescopic observations. The last known ''zij'' treatise was the ''Zij-i Bahadurkhani'', written in 1838 by the Indian astronomer Ghulam Hussain Jaunpuri (1760–1862) and printed in 1855, dedicated to Bahadur Khan. The treatise incorporated the heliocentric system into the ''zīj'' tradition.

List of ''zīj''es

* ''Az-Zīj ‛alā Sinī al-‛Arab'' — by Ibrahim al-Fazari (d. 777) and Muhammad al-Fazari (d. 796/806)
* '' Az-Zīj al-Mahlul min as-Sindhind li-Darajat Daraja'' — by Yaʿqūb ibn Ṭāriq (d. 796)
* ''Zīj al-Sindhind'' — by al-Khwarizmi (c. 780–850)
* ''Az-Zij as-Sabi'' — by Muhammad ibn Jābir al-Harrānī al-Battānī (Albatenius) (853–929)
* ''Zij al-Safa'ih'' (''Tables of the disks of the astrolabe'') — by Abū Ja'far al-Khāzin (900–971)
* ''Zij al-Kabir al-Hakimi'' — by Ibn Yunus (c. 950–1009)
* ''Az-Zīj al-Jamī wal-Baligh'' (''The Comprehensive and Mature Tables'') — by Kushyar ibn Labban (971–1029)
* ''Zīj-i Malik-Shāhī (Astronomical Handbook with Tables for Malikshah)'' (1079) ''—'' by Omar Khayyam (1048–1141)
* '' Almanac of Azarqueil'' (1088) — by Abū Ishāq Ibrāhīm al-Zarqālī (Azarqueil) (1028–1087)
* ''Tables of Toledo'' — based on Abū Ishāq Ibrāhīm al-Zarqālī (Azarqueil) (1028–1087)
* ''Az-Zīj As-Sanjarī'' (''Sinjaric Tables'') — by al-Khazini (fl. 1115–1130)
* '' Zij-i Ilkhani'' — by Nasīr al-Dīn al-Tūsī (1201–1274)
* ''al-Zij al-jadīd —'' by Ibn al-Shāṭir (1304-1375)
* '' Huihui Lifa'' (''Muslim System of Calendrical Astronomy'') — published in China a number of times until the early 18th century,
* ''Khaqani Zij'' — by Jamshīd al-Kāshī (1380–1429)
* ''Zij-i-Sultani'' (1437) — by Ulugh Beg (1393–1449)
* ''Unbored Pearl'' (1579–1580) — by Taqi al-Din Muhammad ibn Ma'ruf (1526–1585)
* ''Zij-i Muhammad Shahi'' — by Jai Singh II of Amber (1688–1743)
* ''Zij-i Bahadurkhani'' (1838) — by Ghulam Hussain Jaunpuri (1760–1862)

See also

* Astrometry
* Epoch (astronomy)
* Ephemeris
* Star catalogue

Notes

References

* E. S. Kennedy. "A Survey of Islamic Astronomical Tables". ''Transactions of the American Philosophical Society'', New Series, 46, 2. Philadelphia, 1956. (A revised version in preparation b
Benno van Dalen
will include over 200 zijes).

Further reading

Islam, Quran and Science: A List of Islamic Astronomical Tables
by Zakaria Virk

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Astronomical works of the medieval Islamic world
Astrological works of the medieval Islamic world
Astronomical tables
Persian words and phrases