History of Astronomy in Iran: An Overview
Mohammad Bagheri (Iran)In a general view, history of astronomy in Iran may be divided into three main
periods: 1) pre-Islamic Iran, 2) Islamic civilization period, and 3) Modern period.
Islam was introduced in Iran around 14 centuries ago. Before that, Iranians
believed in the teachings of the prophet Zoroastre whose exact time is unclear. The
sacred book of Zoroastrians was Avesta composed around 3000 years ago, in
which there is a reference to the spherical shape of the earth. No scientific text
from pre-Islamic Iran has survived. In the Zoroastrian religious texts, somereferences to the names of stars, constellations including zodiacal signs are found.
Prof. Michio Yano has published a horoscope from Bundahishn (lit.: “base ofcreation”), an encyclopedic text from pre-Islamic Iran. Pre-Islamic Iranians
scholars were familiar with Indian and Greek astronomy.
We know that an astronomical work consisting tables of astronomicalparameters and variables plus explanation of the methods of using them wascomposed in pre-Islamic Iran. Such standard handbooks were named zig andMiddle Persian. This Persian term was later Arabicized as az-zij and Latinized asEzich. In Persian the word zig (in modern Persian transformed as zeh) meant“thread” or “chord”. By extension the word came to mean “the set of parallel
threads making up the warp of a fabric”. Then since the closely drawn verticallines of a numerical table are similar to the parallel strings of a textile, the meaning
was further extended to include the former. And finally, the word came to denote
the whole sets of astronomical tables with instructions. The word Qanun (Canon)
was also used for the same meaning.
The astronomical handbook composed in pre-Islamic Iran was called Zij-e Shahor Zij-e Shahriyaran, both meaning “The Royal Astronomical Tables”. In a latertime, it was compared against Ptolemy’s Almagest and an Indian zij (one of theSidhantas) and was revised on the basis of the Indian work referred to as Zig
Hendug (Indian zij) which was found to be better than the Greek one. The firstArabic translation of Almagest into Arabic was from a Pahlavi (Middle Persian)translation.

1After the invasion of Iran by the Muslim Arabs in the 7th century AD, Zij-eShahriyaran was translated into Arabic and the scholars used it and quoted from it
until the 11th century. Today we only have these quoted fragments. Biruni (9731048) and Abu Ma’shar (787-886) are among those who have quoted from the preIslamic zij. Biruni who was the greatest Iranian scholar of the Islamic civilization,
has quoted from Zij-e Shahriyaran the mathematical method of graduation ofhorizontal sundials.
In another Zoroastrian religious book entitled Shayest-Nashayest (lit.: “What todo [and] what not to do”), the lengths of the shadow of a gnomon at midday andafternoon prayer times are provided for each solar month.
I the first century AD, a group of Zoroastrian scholars who were also religious
leaders emigrated from the Sistan province in south-east of Iran to India. They took
their beliefs and knowledge to India and mixed them with Indian beliefs andknowledge. They were called Mugh-Brahmans or Sun worshipper Sistanis and in
Sanskrit they were called Shaka Dvipy. They took also their solar calendar inwhich the year begins with spring equinox. It was called Shaka calendar in India.
The Shaka calendar was the basis of Indian Vikrami calendar which had just a shiftcompared the former. The Vikrami calendar which was based on the Shakacalendar became the official calendar of India after independence in 1947.
From the 7th to the 9th century AD no scientific text has remained because it was
the period of war and resistance against the Arab invaders. Some information about
the Iranian calendar in this period has survived in the work of Anania of Shirak,
the Armenian scholar who flourished in the first century AD.
From the 9th to the 15th century there was a flourishment of scientific activity in
Iran and we find a galaxy of eminent scholars in this period. This was mainly
because the Arabic language became the lingua franca of a vast territory fromSouth Spain (Andalusia) to North Africa, Middle East, and Central Asia up to West
China. There was a lot of scientific exchange and cooperation between scholars ofdifferent language, ethnic origin and even religion. It is sometimes interpreted as
the renaissance of pre-Islamic Iranian science. Most of the works composed werein Arabic, most of the scholars were Iranians and this was the period on Islamiccivilization. So the is a debate on whether it should be called Arabic, Iranian or2

Islamic science. But this is just a matter of terminology which should be a subjectfor conflict.
In the 8th century AD, the Indian astronomical treatise Surya Sidhanta wastranslated into Arabic and influenced the early astronomical works composed inIran. Some Sanskrit terms and methods from Indian astronomy entered Islamic
period astronomy in this way. Dividing the length of a gnomon into 12 parts andthe Sanskrit term bhukti (in Arabic form buht) for the daily mean motion of thecelestial bodies may be mentioned as examples.
About 200 astronomical handbooks (zijes) were composed in the period 9th to15th century AD out of which 100 texts are extant. Only a few of them are edited,translated and published up to now. I have prepared an edition of the Arabic text of
the astronomical work az-Zij al-Jami’ (lit.: “The Comprehensive zij” composed byKushyar ibn Labban (963/4-before 1048 AD) with English translation andcommentary. The Books I and IV of the work have been published in Frankfurt(2009). The remaining Books II and III are being prepared to be published.
The late Prof. E. S. Kennedy composed a book entitled A Survey of Islamic
Astronomical Tables (1956, reprinted in 1989) which is being revised andcompleted by Dr. Benno van Dalen, the Dutch brilliant scholar now based in
Munich. My Persian translation of Kennedy’s book was published in Iran in 1995.
Japanese contemporary scholars have investigated the astronomical legacy ofthe Iranian scientist of the Islamic civilization. Prof. Michio Yano has published anedition of Kushyar ibn Labban’s Arabic treatise entitled An Introduction toAstrology with English translation and old Chinese translation in 1997. Hereceived honorary citizenship of Gilan (birthplace of Kushyar) for this publicationin 2007. He has also translated the astrological treatise of Biruni entitled Tafhim
into Japanese together with the late Prof. Keiji Yamamoto (d. 2018). Thistranslation has been published in three parts in the Kyoto Bulletin of Islamic Area
Studies (March 2010, February 2011 and 2013). Toshikai Kashino has prepared hismaster thesis entitled Planetary Theory of Kushyar ibn Labban in Kyoto Sangyo
University in 1998. Dr. Taro Mimura has prepared and edition of Kushyar ibn
Labban’s Arabic treatise on astrolabe with a Japanese translation as his master3

thesis in Kyoto Sangyo University in 2000. His work has been published in Iran in2013.
The first eminent Iranian astronomer was Muhammad ibn Musa Khwarazmi (9thcentury AD) whose zij was composed in the Indian tradition. The original Arabic
text has not survived, but a Latin translation of a summary of the work has comedown to us. The modern word “algorithm” is said to be a distorted form of theArabic version of his name al-Khwarazmi due to the Latin translation of his bookon arithmetic. He also composed a treatise on algebra and the word algebra, fromthe Arabic term al-jabr (lit.: “compensation”) has found its way into the European
mathematics as the name of the mathematical branch.
Jamshid Kashani (al-Kashi) may be regarded as the last noticeable astronomerof Iran in the Islamic period. He lived in the 15 th century AD. He went from
Kashan to Samarkand on the invitation of Ulugh Beg, the grandson of Tamerlane
who was the ruler of Samarkand. Jamshid Kashani designed an observatory in
Samarkand and made precise and long-run observations there which led to thecomposition of the Persian work Zij-e Soltani (lit.: The Royal zij). Kashani also
calculated a precise value of π which was surpassed by Western mathematicians
only two centuries later. Kashani found an exact value for the sine of one degreeusing an iterative method for solving the involved cubic equation. The method wasdiscovered later in Europe and is named as Newton’s method.
Modern astronomy was introduced in Iran in the 17th century. A trace of thisintroduction is the existence of three similar astrolabes kept in Cambridge(Whipple Museum of History of Science), Greenwich (The National MaritimeMuseum) and a private collection in Antwerp. They are made by a certain
Muhammad Mehdi Khadem Yazdi in 1070 AH/ 1659-60 AD. The date ismentioned in the form of a poem engraved on them using the abjad alphanumericalsystem. On one of the plates relating to the constellations of the northern celestialhemisphere the following fragment is engraved in Persian: “Since there were somedeviations in the positions of the fixed stars based on the old observations, and themost accurate positions of the fixed stars were found by the European observations,
we based the positions of the fixed stars in this plate on their observations carriedout ten years ago.” This was possibly the celestial map prepared by Melchior4Tavernier in Paris in 1650. Tavernier’s brother visited Iran in 1651 and was incontact with the court of the Safavid dynasty king of Iran.
At present, there are research and educational astronomical observatories inseveral cities of Iran. The National Observatory of Iran is being constructed near
the city Qum (Iran). Astronomy and astrophysics is taught in several universities ofIran. There is a master program in history of astronomy in the Institute for theHistory of science, University of Tehran. Several journals and books are publishedin Iran in the field of astronomy.
Amateur astronomy has a noticeable growth in Iran in the recent 20 years.
Amateur astronomical societies actively cooperate and establish scientificcooperation with other societies inside or outside Iran.
I organized a workshop on origami sundials in Mehr Astronomical Society inBushehr, a city in the south of Iran, on the coast of the Persian Gulf. In anotheramateur astronomical society Sagheb in the city of Rasht, in the north of Iran, near
the Caspian Sea, there is noticeable activity in the history of astronomy andgnomonics (the science of making and using sundials). There are several modern
sundials in this city and a sundial excursion was recently organized there. The lastsundial made in Iran was designed by me recently. I append here a photo of thisverticalsundialsituated in Apadana
Residence Complex
in west of Tehran.
Sundials have a long
history in Iran, fromthe pre-Islamic era to
the Islamic period andmodern times. They
are regarded efficient
tools to raise curiosity
towards
astronomy
among the younger
generations.

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