The Great Contribution of Islamic Astronomers

[Bianca]

Islamic astronomy in China



See also: Chinese astronomy

Muslim astronomers were brought to China work on calendar making and astronomy during the Yuan Dynasty.

Kublai Khan brought Iranians to Beijing to construct an observatory and an institution for astronomical studies.  Jamal ad-Din, a Persian astronomer, presented Kublai Khan with seven Persian astronomical instruments, including a Persian globe and an armillary sphere, in 1267.

Several Chinese astronomers also worked at the Maragheh observatory in Persia.




1450-1900



This period was considered the period of stagnation, when the traditional system of astronomy continued to be practised with enthusiasm, but with decreasing innovation.

It was believed there was no innovation of major significance during this period, but this view has been rejected by historians of astronomy in recent times, who argue that Muslim astronomers continued to make significant advances in astronomy through to the 16th century and possibly after this as well.

After the 16th century, there appears to have been little concern for theoretical astronomy, but observational astronomy in the Islamic tradition continued in the three Muslim gunpowder empires: the Ottoman Empire, the Safavid dynasty of Persia, and the Mughal Empire of India.

[Bianca]

Earth's motion
 


Ali al-Qushji provided empirical evidence for the Earth's motion and completely separated astronomy from natural philosophy.The work of Ali al-Qushji (d. 1474), who worked at Samarkand and then Istanbul, is seen as a late example of innovation in Islamic astronomy and it is believed he may have had an influence on Nicolaus Copernicus due to similar arguments concerning the Earth's rotation.

Before al-Qushji, the only astronomer to present an empirical argument for the Earth's rotation was Nasīr al-Dīn al-Tūsī (d. 1274), who used the phenomena of comets to refute Ptolemy's claim that a stationery Earth can be determined through observation alone. Al-Tusi, however, accepted that the Earth was stationery on the basis
of natural philosophy instead, particularly Aristotelian cosmology.

In the 15th century, the influence of Aristotelian physics and natural philosophy was declining due to religious opposition.

Al-Qushji, in his Concerning the Supposed Dependence of Astronomy upon Philosophy, thus rejected Aristotelian physics and completely separated natural philosophy from astronomy, allowing astronomy to become a purely empirical and mathematical science. This allowed him to explore alternatives to the Aristotelian notion of a stationery Earth, as he explored the idea of a moving Earth. He elaborated on al-Tusi's argument and concluded, on the basis of empiricism rather than speculative philosophy, that the moving Earth theory is just as likely to be true as the stationary Earth theory and that it is not possible to empirically deduce which theory is true.

In the 16th century, the debate on the Earth's motion was continued by al-Birjandi (d. 1528), who in his analysis of what might occur if the Earth were rotating, develops a hypothesis similar to Galileo Galilei's notion of "circular inertia", which he described in the following observational test (as a response to one of Qutb al-Din al-Shirazi's arguments):

"The small or large rock will fall to the Earth along the path of a line that is perpendicular to the plane (sath) of the horizon; this is witnessed by experience (tajriba). And this perpendicular is away from the tangent point of the Earth’s sphere and the plane of the perceived (hissi) horizon. This point moves with the motion of the Earth and thus there will be no difference in place of fall of the two rocks."

[Bianca]

Theoretical astronomy



It was traditionally believed that Islamic astronomers made no more advances in planetary theory after the work of Ibn al-Shatir in the 14th century, but recent studies have shown that there were several significant advances in planetary theory through to the 16th century, after George Saliba studied the works of a 16th century astronomer, Shams al-Din al-Khafri (d. 1550), a Safavid commentator on earlier Maragha astronomers. Saliba wrote the following on al-Khafri's work:




"By his sheer insight into the role of mathematics in describing natural phenomena, this astronomer managed to bring the hay'a tradition to such unparalleled heights that could not be matched anywhere else in the world at that time neither mathematically nor astronomically.

By working on the alternative mathematical models that could replace those of Ptolemy, and by scrutinizing the works of his predecessors who were all searching for unique mathematical models that could describe the physical phenomena consistently, this astronomer finally realized that all mathematical modeling had no physical truth by itself and was simply another language with which one could describe the physical observed reality.

He also realized that the specific phenomena that were being described by the Ptolemaic models did not have unique mathematical solutions that were subject to the same restraints.

Rather, there were several mathematical models that could account for the Ptolemaic observations, yield identical predictive results at the same critical points used by Ptolemy to construct his own models (thus accounting for the observations as perfectly as Ptolemy could) and still meet the consistency requirement that was imposed by the Aristotelian cosmology which was adopted by the writers in the hay'a tradition."




Ali al-Qushji also improved on al-Tusi's planetary model and presented an alternative planetary model for Mercury

[Bianca]

 





A model of the heliocentric system attributed to Nicolaus Copernicus.

[Bianca]

Ottoman observational astronomy



Another notable 16th century Muslim astronomer was the Ottoman astronomer Taqi al-Din, who built the Istanbul observatory of al-Din in 1577, where he carried out astronomical observations until 1580.

He produced a Zij (named Unbored Pearl) and astronomical catalogues that were more accurate than those of his contemporaries, Tycho Brahe and Nicolaus Copernicus.

Al-Din was also the first astronomer to employ a decimal point notation in his observations rather than the sexagesimal fractions used by his contemporaries and predecessors.[108] He also invented a variety of astronomical instruments, including accurate mechanical astronomical clocks from 1556 to 1580 and a rudimentary telescope some time before 1574.

Earlier in 1574, al-Din used astrophysics to explain the intromission model of vision. He stated since the stars are millions of kilometers away from the Earth and that the speed of light is constant, that if light had come from the eye, it would take too long for light "to travel to the star and come back to the eye. But this is not the case, since we see the star as soon as we open our eyes. Therefore the light must emerge from the object not from the eyes."

After the destruction of the Istanbul observatory of al-Din in 1580, astronomical activity stagnated in the Ottoman Empire, until the introduction of Copernican heliocentrism in 1660, when the Ottoman scholar Ibrahim Efendi al-Zigetvari Tezkireci translated Noël Duret's French astronomical work (written in 1637) into Arabic.

[Bianca]

Islamic astronomy in India


See also: Indian astronomy



Meanwhile in the Mughal Empire, the 16th and 17th centuries saw a synthesis between Islamic and Indian astronomy, where Islamic observational techniques and instruments were combined with Hindu computational techniques.

While there appears to have been little concern for theoretical astronomy, Muslim and Hindu astronomers in India continued to make advances in observational astronomy and produced nearly a hundred Zij treatises. Humayun built a personal observatory near Delhi, while Jahangir and Shah Jahan were also intending to build observatories but were unable to do so.

After the decline of the Mughal Empire, however, it was a Hindu king, Jai Singh II of Amber, who attempted to revive the Islamic tradition of astronomy in India. In the early 18th century, he built several large observatories called Yantra Mandirs in order to rival the famous Samarkand observatory, and in order to update Ulugh Beg's Zij-i-Sultani with more accurate observations.

The instruments and observational techniques used at the observatory were mainly derived from the Islamic tradition, and the computational techniqes from the Hindu tradition.  In particular, one of the most remarkable astronomical instruments invented by Muslims in Mughal India is the seamless celestial globe (see Globes below).

Jai Singh also invited European Jesuit astronomers to his observatory, who had bought back the astronomical tables compiled by Philippe de La Hire in 1702. After examining La Hire's work, Jai Singh concluded that the techniques and instruments used in the European tradition were inferior to the Islamic and Indian traditions.

It is uncertain whether Islamic astronomers in India were aware of the Copernican Revolution via the Jesuits, but it appears they were not concerned with theoretical astronomy, hence the theoretical advances in Europe did not interest them at the time.

[Bianca]

Kerim Kerimov,
one of the founders of the
Soviet space program.











1900-present



In the 20th and 21st centuries, Muslim astronomers have been making advances in moon sighting, while Muslim astronauts and rocket scientists have been involved in research on astronautics and space exploration.






Muslim participation in astronautics and space exploration
 


Kerim Kerimov from Azerbaijan (then part of the Soviet Union) was one of the most important key figures in early space exploration. He was one of the founders of the Soviet space program, one of the lead architects behind the first human spaceflight (Vostok 1), and responsible for the launch of the first space stations (the Salyut and Mir series) as well as their predecessors (the Cosmos 186 and Cosmos 188).

Farouk El-Baz from Egypt worked for the rival NASA and was involved in the first Moon landings with the Apollo program, where he was secretary of the Landing Site Selection Committee, Principal Investigator of Visual Observations and Photography, chairman of the Astronaut Training Group, and assisted in the planning of scientific explorations of the Moon, including the selection of landing sites for the Apollo missions and the training of astronauts in lunar observations and photography.

In the late 20th and early 21st centuries, there have also been a number of Muslim astronauts, the first being Sultan bin Salman bin Abdulaziz Al Saud as a Payload Specialist aboard STS-51-G Space Shuttle Discovery, followed by Muhammed Faris aboard Soyuz TM-2 and Soyuz TM-3 to Mir space station; Abdul Ahad Mohmand aboard Soyuz TM-5 to Mir; Talgat Musabayev (one of the top 25 astronauts by time in space) as a flight engineer aboard Soyuz TM-19 to Mir, commander of Soyuz TM-27 to Mir, and commander of Soyuz TM-32 and Soyuz TM-31 to International Space Station (ISS); and Anousheh Ansari, the first woman to travel to ISS and the fourth space tourist.

In 2007, Sheikh Muszaphar Shukor from Malaysia traveled to ISS with his Expedition 16 crew aboard Soyuz TMA-11 as part of the Angkasawan program during Ramadan, for which the National Fatwa Council wrote Guidelines for Performing Islamic Rites (Ibadah) at the International Space Station, giving advice on issues such as prayer in a low-gravity environment, the location of Mecca from ISS, determination of prayer times, and issues surrounding fasting.

Shukor also celebrated Eid ul-Fitr aboard ISS. He was both an astronaut and an orthopedic surgeon, and is most notable for being the first to perform biomedical research in space, mainly related to the characteristics and growth of liver cancer and leukemia cells and the crystallization of various proteins and microbes in space.

Other prominent Muslim scientists involved in research on the space sciences and space exploration include Essam Heggy who is working in the NASA Mars Exploration Program in the Lunar and Planetary Institute in Houston, as well as Ahmed Salem, Alaa Ibrahim, Mohamed Sultan, and Ahmed Noor.

[Bianca]

New efforts in moon sighting



According to Islam, Muslims should observe religious duties during special days on the basis of the Islamic lunar calendar. Therefore, moon sighting is an important issue for Muslims.

In recent years, due to global communication and using modern technologies to see the new moon,
a new trend has formed among Muslims in this field and new religious questions have emerged.

In 2005, Ayatollah Ali Khamenei, religious scholar and supreme leader of Iran, issued a fatwa to use modern technologies for moon sighting. The Islamic Society of North America in Plainfield, Ind., followed suit last year. Muslims are scrambling for a technological edge in the annual moon-hunting ritual.

Ayatollah Khamenei has established a Moon Observation Committee, composed of clerics who pore over sightings reported to centers. Scientists note the moon's angle, position, and illumination, and compare the sightings from the field with computerized charts that pinpoint where the moon should be. In Iran, groups of astronomers accompanied by a cleric are dispatched across the country, some using night vision gear lent by the military of Iran and high-definition telescopes from the universities. Iran also sends up a chartered airplane with an astronomer aboard.

The plane is loaded with sensitive observation and photographic equipment, along with a laptop. Iranian mapmakers at the National Geography Organization in Tehran have created a three-dimensional map of the country identifying 70 locations where the new moon might best be seen.

There are similar efforts in other Muslim countries as well.

There is also a competition among astronomers to see the younger moon with naked eyes. According to the Islamic lunar calendar in Iran, the new "World Record for Lunar Crescent Sighting" has been established on September 7, 2002 (Jamadi-al Thani 29, 1423 AH) by Mohsen Ghazi Mirsaeed on the north-west heights (2,110 meters ) of Zarand in Rashk Bala village (31°, 04' N , 56°, 28' E). The record for the moon age at the moment of first visibility with naked eyes is 11 hours and 42 minutes.

[Bianca]

Observatories



The modern astronomical observatory as a research institute (as opposed to a private observation post as was the case in ancient times was first introduced by medieval Muslim astronomers, who produced accurate Zij treatises using these observatories.

The Islamic observatory was the first specialized astronomical institution with its own scientific staff, director, astronomical program,[ large astronomical instruments, and building where astronomical research and observations are carried out. Islamic observatories were also the first to employ enormously large astronomical instruments in order to improve the accuracy of their observations.

The medieval Islamic observatories were also the earliest institutions to emphasize group research (as opposed to individual research) and where "theoretical investigations went hand in hand with observations." In this sense, they were similar to modern scientific research institutions.

[Bianca]

Early observatories



The first systematic observations in Islam are reported to have taken place under the patronage of al-Ma'mun, and the first Islamic observatories were built in 9th century Iraq under his patronage. In many private observatories from Damascus to Baghdad, meridian degrees were measured, solar parameters were established, and detailed observations of the Sun, Moon, and planets were undertaken.

In the 10th century, the Buwayhid dynasty encouraged the undertaking of extensive works in Astronomy, such as the construction of a large scale instrument with which observations were made
in the year 950. We know of this by recordings made in the zij of astronomers such as Ibn al-Alam.

The great astronomer Abd Al-Rahman Al Sufi was patronised by prince 'Adud al-Dawla, who systematically revised Ptolemy's catalogue of stars. Abu-Mahmud al-Khujandi also constructed an observatory in Ray, Iran where he is known to have constructed the first huge mural sextant in 994 AD.

Sharaf al-Daula also established a similar observatory in Baghdad. Reports by Ibn Yunus and al-Zarqall in Toledo and Cordoba indicate the use of sophisticated instruments for their time.

It was Malik Shah I who established the first large observatory, probably in Isfahan. It was here where Omar Khayyám with many other collaborators constructed a zij and formulated the Persian solar calendar, a.k.a. the jalali calendar, the most accurate solar calendar to date. A modern version of this calendar is still in official use in Iran today.

[Bianca]

Current status of Maragheh observatory.

[Bianca]

Late medieval observatories



Further information: Maragheh observatory and Istanbul observatory of al-Din
The more influential observatories, however, were established beginning in the 13th century.

The Maragheh observatory was founded by Nasīr al-Dīn al-Tūsī under the patronage of Hulegu Khan in the 13th century. Here, al-Tusi supervised its technical construction at Maragheh. The facility contained resting quarters for Hulagu Khan, as well as a library and mosque.

Some of the top astronomers of the day gathered there, and their collaboration resulted in important alternatives to the Ptolemaic model over a period of 50 years. The observations of al-Tusi and his team of researchers were compiled in the Zij-i Ilkhani.

 
Ulugh Beg, founder of a large Islamic observatory in Samarkand, honored on this Soviet stamp.In 1420, prince Ulugh Beg, himself an astronomer and mathematician, founded another large observatory in Samarkand, the remains of which were excavated in 1908 by Russian teams. In 1577, Taqi al-Din bin Ma'ruf founded the large Istanbul observatory of al-Din, which was on the same scale as those in Maragha and Samarkand.

In the Mughal Empire, Humayun built a personal observatory near Delhi in the 16th century, while Jahangir and Shah Jahan were also intending to build observatories but were unable to do so.

After the decline of the Mughal Empire, the Hindu king Jai Singh II of Amber built several large observatories called Yantra Mandirs inspired by the famous Samarkand observatory. The instruments and observational techniques used at the observatory were mainly derived from the Islamic tradition, and the computational techniqes from the Hindu tradition.

[Bianca]

 Ulugh Beg,
founder of a large Islamic observatory in Samarkand,
honored on this Soviet stamp.

[Bianca]

Modern observatories



In modern times, many well-equipped observatories can be found



in Jordan,

Palestine,

Lebanon,

UAE,

Tunisia, and

other Arab states are also active as well. Iran has modern facilities at Shiraz University and Tabriz University. In December 2005, Physics Today reported of Iranian plans to construct a "world class" facility with a 2.0 meter telescope observatory in the near future.







Instruments



See also: Inventions in the Muslim world


Modern knowledge of the instruments used by Muslim astronomers primarily comes from two sources. First the remaining instruments in private and museum collections today, and second the treatises and manuscripts preserved from the Middle Ages.

Muslims made many improvements to instruments already in use before their time, such as adding new scales or details, and invented many of their own new instruments. Their contributions to astronomical instrumentation are abundant.

Many of these instruments were often invented or designed for Islamic purposes, such as the determination of the Qibla (direction to Mecca) or the times of Salah prayers.

[Bianca]

 Astrolabes



Brass astrolabes were developed in much of the Islamic world, often as an aid to finding the qibla.
The earliest known example is dated 315 (in the Islamic calendar, corresponding to 927-8CE).

The first person credited for building the Astrolabe in the Islamic world is reportedly Fazari.

Though the first primitive astrolabe to chart the stars was invented in the Hellenistic civilization, al-Fazari made several improvements to the device.

The Arabs then took it during the Abbasid Caliphate and perfected it to be used to find the beginning of Ramadan, the hours of prayer (Salah), the direction of Mecca (Qibla), and over a thousand other uses.

In the 10th century, al-Sufi first described over 1000 different uses of an astrolabe, in areas as diverse as astronomy, astrology, horoscopes, navigation, surveying, timekeeping, Qibla, Salah, etc.[