In its origins and development, Islamic astronomy closely parallels the genesis of other Islamic sciences in its assimilation of foreign material and the amalgamation of the disparate elements of that material to create a science that was essentially Islamic. These include Indian and Sassanid works in particular. Some Hellenistic texts were also translated and built upon as well.

Some stars in the sky, such as Aldebaran, are still today recognized with their Arabic names.

Science historian Donald. R. Hill has divided Islamic Astronomy into four distinct time periods in its history:

700-825 CE: The period of assimilation and syncretisation of earlier Hellenistic, Indian, and Sassanid astronomy.
825-1025 CE: The period of vigorous investigation, in which the superiority of the Ptolemaic system of astronomy was accepted and significant contributions made to it.
1025-1450 CE: The period when a distinctive Islamic system of astronomy flourished.
1450-1900 CE: The period of stagnation, when the traditional system of astronomy continued to be practised with enthusiasm, but with rapidly decreasing innovation of any major significance.

A large corpus of literature from Islamic astronomy remains today, numbering around some 10,000 manuscript volumes scattered throughout the world. Much of which has not even been catalogued. Even so, a reasonably accurate picture of Islamic activity in the field of astronomy can be reconstructed.

1 Celestial passages in the Qur'an
2 Observatories
3 Instruments
4 Muslim astronomers
5 Famous Muslim astronomy books
6 Notes
7 References
8 See also
9 External links

[edit] Celestial passages in the Qur'an

Some Muslims quote verses from the Qur'an that show God encourages people to engage in astronomy, in order to affirm the existence of God.

Regarding astronomy:

Sura 3.190

In the creation of the heavens and the earth and in the alternation of the night and the day there are indeed Signs for men of understanding.;

Sura 67.3-4

Who has created seven heavens in harmony. No incongruity canst thou see in the creation of the Gracious God. Then look again. Seest thou any flaw?

Image:Book Al Sufi.jpg

Regarding Physical cosmology:

Sura 21.30

Do not the disbelievers see that the heavens and the earth were a closed up-mass, then WE opened them out? And WE made of water every living thing. Will they not then believe?

Sura 41.11

Then HE turned to the heaven, while it was something like smoke, and said to it and to the earth; `Come ye both of you in obedience, willingly or unwillingly.' They said, `We come willingly. [1]

[edit] Observatories

Medieval manuscript by Qotbeddin Shirazi depicting an epicyclic planetary model.

The first systematic observations in Islam are reported to have taken place under the patronage of al-Mamun. Here, and in many other 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 950CE. 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 o-dowleh, who systematically revised Ptolemy's catalogue of stars. Sharaf al-Daula also established a similar observatory in Baghdad. And 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. A modern version of this calendar is still in official use in Iran today.

The most influential observatory was however founded by Hulegu Khan during the 13th century. Here, Nasir al-Din al-Tusi supervised its technical construction at Maragha. 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 from their collaboration resulted important modifications to the Ptolemaic system over a period of 50 years.

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.

And finally, Taqi al-din bin Ma'ruf founded a large observatory in Istanbul in 1575, which was on the same scale as those in Maragha and Samarkand.

In modern times, Turkey [2][3]has many well equipped observatories, while Jordan [4], Palestine [5], Lebanon [6], UAE [7], Tunisia [8], and other Arab states are also active as well. Iran has modern facilities at Shiraz University and Tabriz University. In Dec 2005, Physics Today reported of Iranian plans to construct a "world class" facility with a 2.0 m telescope observatory in the near future.[9]

[edit] Instruments

Our 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. Their contributions to astronomical instrumentation are abundant.

[edit] Celestial globes and armillary spheres

Celestial globes were used primarily for solving problems in celestial astronomy. Today, 126 such instruments remain worldwide, the oldest from the 11th century. The altitude of the sun, or the Right Ascension and Declination of stars could be calculated with these by inputting the location of the observer on the meridian ring of the globe.

An armillary sphere had similar applications. No early Islamic armillary spheres survive, but several treatises on “the instrument with the rings” were written. In this context there is also an Islamic development, the spherical astrolabe, of which only one complete instrument, from the 14th century, has survived.

[edit] Astrolabes

Image:Astrolabe-Persian-18C.jpg

Brass astrolabes were developed in much of the Islamic world, chiefly 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 (Richard Nelson Frye: Golden Age of Persia. p163). He only improved it though, the Greeks had already invented astrolabes to chart the stars. The Arabs then took it during the Abbasid Dynasty and perfected it to be used to find the beginning of Ramadan, the hours of prayer, and the direction of Mecca.

The instruments were used to read the rise of the time of rise of the Sun and fixed stars. al-Zarqall of Andalusia constructed one such instrument in which, unlike its predecessors, did not depend on the latitude of the observer, and could be used anywhere. This instrument became known in Europe as the Saphaea.

[edit] Sundials

Muslims made several important improvements to the theory and construction of sundials, which they inherited from their Indian and Greek predecessors. Khwarizmi made tables for these instruments which considerably shortened the time needed to make specific calculations.

Sundials were frequently placed on mosques to determine the time of prayer. One of the most striking examples was built in the 14th century by the muwaqqit (timekeeper) of the Umayyid Mosque in Damascus, ibn al-Shatir.<ref>David A. King, "Islamic Astronomy," pp. 168-9.</ref>

[edit] Quadrants

Several forms of quadrants were invented by Muslims. Among them was the sine quadrant used for astronomical calculations and various forms of the horary quadrant, used to determine time (especially the times of prayer) by observations of the Sun or stars. A center of the development of quadrants was ninth-century Baghdad.<ref>David A. King, "Islamic Astronomy," pp. 167-8.</ref>

[edit] Equatorium

The Equatorium is an Islamic invention from Andalusia. The earliest known was probably made around 1015 CE. It is a mechanical device for finding the positions of the Moon, Sun, and planets, without calculation using a geometrical model to represent the celestial body's mean and anomalistic position.

[edit] Muslim astronomers

Main article: Muslim astronomers

[edit] Famous Muslim astronomy books

al-Khwarizmi (c. 830), Zij al-Sindhind
al-Farghani (d. c. 850), Kitab fi Jawami Ilm al-Nujum

[edit] Notes

[edit] References

Donald R. Hill, Islamic Science And Engineering, Edinburgh University Press (1993), ISBN 0-7486-0455-3
David A. King: "Islamic Astronomy", in Astronomy before the telescope, ed. Christopher Walker. British Museum Press, (1999), pp. 143-174. ISBN 0-7141-2733-7