Zij-i Ilkhani
Encyclopedia
Zīj-i Īlkhānī or Ilkhanic Tables (literal translation: "The Ilkhan Stars", after ilkhan Hulagu, who was the patron of the author at that time) is a Zij
book with astronomical tables
of planetary movements. It was compiled by the Persian
astronomer Nasir al-Din al-Tusi
in collaboration with his research team of astronomers at the Maragha observatory. It was written in Persian
and later translated into Arabic
.
The book contains tables for calculating the positions of the planets and the names of the stars. It included data derived from the observations of the stars and planets over 12 years in the Maragha observatory, completed in 1272. The planetary Positions of the Zij-i Ilkhani, derived from the Zijs of Ibn Al-`Alam and Ibn Yunis (ct. 10 AD), was so fault that astronomers of the latter periods, such as Shams al-Din Muhammad al-Wabkanawi (1254-1320 AD) and Rukn al-DIn al-Amuli , made severely critiques on it.
The Zīj-i Īlkhānī set the precession of the equinoxes at 51 degrees per annum, which is very close to the modern value of 50.2 degrees. The book also describes a method of interpolation
between the observed positions, which in modern terms may be described as a second-order interpolation scheme. Of course, various kinds of interpolation had been known since Ptolemy
and more likely before him in antiquity.
s), especially of al-Tusi. Therefore when al-Tusi complained that his astromical tables were 250 years old, Hulagu gave permission to build a new observatory in a place of al-Tusi's choice (he chose Maragheh
). A number of other prominent astronomers worked with al-Tusi there, including Muhyi al-Din al-Maghribi
, Qutb al-Din al-Shirazi
, Mu'ayyid al-Din al-'Urdi from Damascus
, and Hulagu's Chinese astronomer Fao Munji whose Chinese astronomical experience brought improvements to Ptolemaic
system used by al-Tusi - traces of the Chinese system may be seen in Zij-i Ilkhani. The tables were published during the reign of Abaqa Khan
, Hulagu's son, and named after the patron of the observatory. They were popular until the 15th century.
Some Islamic astronomical tables such as the Zij-i Al-`Ala'i of Abd-Al-Karim al-Fahhad and the Zij al-Sanjari of Khazini were translated into Byzantine Greek by Gregory Choniades
and studied in the Byzantine Empire
. Chioniades himself had studied under Shams ad-Din al-Bukhari, who had worked at the famous Maragheh observatory
after the death of al-Tusi.
Zij
Zīj is the generic name applied to Islamic astronomical books that tabulate parameters used for astronomical calculations of the positions of the Sun, Moon, stars, and planets. The name is derived from the Middle Persian term zih or zīg, meaning cord...
book with astronomical tables
Ephemeris
An ephemeris is a table of values that gives the positions of astronomical objects in the sky at a given time or times. Different kinds of ephemerides are used for astronomy and astrology...
of planetary movements. It was compiled by the Persian
Persian people
The Persian people are part of the Iranian peoples who speak the modern Persian language and closely akin Iranian dialects and languages. The origin of the ethnic Iranian/Persian peoples are traced to the Ancient Iranian peoples, who were part of the ancient Indo-Iranians and themselves part of...
astronomer Nasir al-Din al-Tusi
Nasir al-Din al-Tusi
Khawaja Muḥammad ibn Muḥammad ibn Ḥasan Ṭūsī , better known as Naṣīr al-Dīn al-Ṭūsī , was a Persian polymath and prolific writer: an astronomer, biologist, chemist, mathematician, philosopher, physician, physicist, scientist, theologian and Marja Taqleed...
in collaboration with his research team of astronomers at the Maragha observatory. It was written in Persian
Persian language
Persian is an Iranian language within the Indo-Iranian branch of the Indo-European languages. It is primarily spoken in Iran, Afghanistan, Tajikistan and countries which historically came under Persian influence...
and later translated into Arabic
Arabic language
Arabic is a name applied to the descendants of the Classical Arabic language of the 6th century AD, used most prominently in the Quran, the Islamic Holy Book...
.
The book contains tables for calculating the positions of the planets and the names of the stars. It included data derived from the observations of the stars and planets over 12 years in the Maragha observatory, completed in 1272. The planetary Positions of the Zij-i Ilkhani, derived from the Zijs of Ibn Al-`Alam and Ibn Yunis (ct. 10 AD), was so fault that astronomers of the latter periods, such as Shams al-Din Muhammad al-Wabkanawi (1254-1320 AD) and Rukn al-DIn al-Amuli , made severely critiques on it.
The Zīj-i Īlkhānī set the precession of the equinoxes at 51 degrees per annum, which is very close to the modern value of 50.2 degrees. The book also describes a method of interpolation
Interpolation
In the mathematical field of numerical analysis, interpolation is a method of constructing new data points within the range of a discrete set of known data points....
between the observed positions, which in modern terms may be described as a second-order interpolation scheme. Of course, various kinds of interpolation had been known since Ptolemy
Ptolemy
Claudius Ptolemy , was a Roman citizen of Egypt who wrote in Greek. He was a mathematician, astronomer, geographer, astrologer, and poet of a single epigram in the Greek Anthology. He lived in Egypt under Roman rule, and is believed to have been born in the town of Ptolemais Hermiou in the...
and more likely before him in antiquity.
History
Hulagu Khan believed that many his military successes were due to the advice of astronomers (who were also astrologerAstrologer
An astrologer practices one or more forms of astrology. Typically an astrologer draws a horoscope for the time of an event, such as a person's birth, and interprets celestial points and their placements at the time of the event to better understand someone, determine the auspiciousness of an...
s), especially of al-Tusi. Therefore when al-Tusi complained that his astromical tables were 250 years old, Hulagu gave permission to build a new observatory in a place of al-Tusi's choice (he chose Maragheh
Maragheh
Maragheh also Romanized as Marāgheh and Marāghen) is a city in and the capital of Maragheh County, East Azerbaijan Province, Iran. At the 2006 census, its population was 146,405, in 38,891 families....
). A number of other prominent astronomers worked with al-Tusi there, including Muhyi al-Din al-Maghribi
Muhyi al-Din al-Maghribi
', was a Muslim astronomer and mathematician born in Spain, worked in Damascus, Syria and eventually in the Maragha observatory in Maragha, Ilkhanate of Persia, where he worked under the guidance of Nasir al-Din Tusi.Muhyi al-Din is most known for his works in trigonometry, Book on the theorem...
, Qutb al-Din al-Shirazi
Qutb al-Din al-Shirazi
Qotb al-Din Shirazi or Qutb al-Din al-Shirazi was a 13th century Persian Muslim polymath and Persian poet who made contributions astronomy, mathematics, medicine, physics, music theory, philosophy and Sufism.- Biography :...
, Mu'ayyid al-Din al-'Urdi from Damascus
Damascus
Damascus , commonly known in Syria as Al Sham , and as the City of Jasmine , is the capital and the second largest city of Syria after Aleppo, both are part of the country's 14 governorates. In addition to being one of the oldest continuously inhabited cities in the world, Damascus is a major...
, and Hulagu's Chinese astronomer Fao Munji whose Chinese astronomical experience brought improvements to Ptolemaic
Ptolemy
Claudius Ptolemy , was a Roman citizen of Egypt who wrote in Greek. He was a mathematician, astronomer, geographer, astrologer, and poet of a single epigram in the Greek Anthology. He lived in Egypt under Roman rule, and is believed to have been born in the town of Ptolemais Hermiou in the...
system used by al-Tusi - traces of the Chinese system may be seen in Zij-i Ilkhani. The tables were published during the reign of Abaqa Khan
Abaqa Khan
Abaqa Khan , also Abaga , or Abagha Khan, was the second Mongol ruler of the Persian Ilkhanate. The son of Hulagu Khan and Yesuncin Khatun, he reigned from 1265–1282 and was succeeded by his brother Tekuder Khan...
, Hulagu's son, and named after the patron of the observatory. They were popular until the 15th century.
Some Islamic astronomical tables such as the Zij-i Al-`Ala'i of Abd-Al-Karim al-Fahhad and the Zij al-Sanjari of Khazini were translated into Byzantine Greek by Gregory Choniades
Gregory Choniades
Gregory Choniades was a Byzantine Greek astronomer. He travelled to Persia where he learnt Persian mathematical and astronomical science which he introduced into Byzantium upon return from Persia and founded an astronomical academy at Trebizond...
and studied in the Byzantine Empire
Byzantine Empire
The Byzantine Empire was the Eastern Roman Empire during the periods of Late Antiquity and the Middle Ages, centred on the capital of Constantinople. Known simply as the Roman Empire or Romania to its inhabitants and neighbours, the Empire was the direct continuation of the Ancient Roman State...
. Chioniades himself had studied under Shams ad-Din al-Bukhari, who had worked at the famous Maragheh observatory
Maragheh observatory
Maragheh observatory is an astronomical observatory which was established in 1259 CE by Nasir al-Din al-Tusi, an Iranian scientist and astronomer...
after the death of al-Tusi.