Al-Khalili
Encyclopedia
was an astronomer
of Syria
who compiled extensive tables for astronomical use.
Shams al-Din Abu Abdullah Muhammad ibn Muhammad al-Khalili worked in Damascus
, Syria at the Umayyad Mosque
as a religious timekeeper (muwaqqit) for the majority of his life. Other than al-Khalili’s occupation, little is known about his life. He lived at the same time as Ibn al-Shatir
, the famous Arab astronomer.
Al-Khalili is known for two sets of mathematical tables he constructed, both totaling roughly 30,000 entries. He tabulated all the entries made by the celebrated Egyptian Muslim astronomer Ibn Yunus
, except for the entries that al-Khalili made himself for the city of Damascus. It is evident that number manipulation did not exhaust al-Khalili as he computed 13,000 entries into his ‘Universal Tables’ of different auxiliary functions which allowed him to generate the solutions of standard problems of spherical astronomy for any given latitude. In addition to this, he created a 3,000 entry table that gave the direction of the city of Mecca
(the Qibla
) for all latitudes and longitudes for all the Muslim countries of the 14th century. Knowledge of the direction of the Qibla is essential in Islam because Muslims pray in the direction of Mecca. The values present in al-Khalili’s tables have been determined to be amazingly accurate – indeed they have been calculated to be accurate up to three or four significant decimal digits. Up to the present time, it is not known how exactly al-Khalili went about calculating each of his entries.
Astronomer
An astronomer is a scientist who studies celestial bodies such as planets, stars and galaxies.Historically, astronomy was more concerned with the classification and description of phenomena in the sky, while astrophysics attempted to explain these phenomena and the differences between them using...
of Syria
Syria
Syria , officially the Syrian Arab Republic , is a country in Western Asia, bordering Lebanon and the Mediterranean Sea to the West, Turkey to the north, Iraq to the east, Jordan to the south, and Israel to the southwest....
who compiled extensive tables for astronomical use.
Shams al-Din Abu Abdullah Muhammad ibn Muhammad al-Khalili worked in 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...
, Syria at the Umayyad Mosque
Umayyad Mosque
The Umayyad Mosque, also known as the Great Mosque of Damascus or formerly the Basilica of Saint John the Baptist , is located in the old city of Damascus, is one of the largest and oldest mosques in the world...
as a religious timekeeper (muwaqqit) for the majority of his life. Other than al-Khalili’s occupation, little is known about his life. He lived at the same time as Ibn al-Shatir
Ibn al-Shatir
Ala Al-Din Abu'l-Hasan Ali Ibn Ibrahim Ibn al-Shatir was an Arab Muslim astronomer, mathematician, engineer and inventor who worked as muwaqqit at the Umayyad Mosque in Damascus, Syria.-Astronomy:...
, the famous Arab astronomer.
Al-Khalili is known for two sets of mathematical tables he constructed, both totaling roughly 30,000 entries. He tabulated all the entries made by the celebrated Egyptian Muslim astronomer Ibn Yunus
Ibn Yunus
Ibn Yunus was an important Egyptian Muslim astronomer and mathematician, whose works are noted for being ahead of their time, having been based on meticulous calculations and attention to detail.The crater Ibn Yunus on the Moon is named after...
, except for the entries that al-Khalili made himself for the city of Damascus. It is evident that number manipulation did not exhaust al-Khalili as he computed 13,000 entries into his ‘Universal Tables’ of different auxiliary functions which allowed him to generate the solutions of standard problems of spherical astronomy for any given latitude. In addition to this, he created a 3,000 entry table that gave the direction of the city of Mecca
Mecca
Mecca is a city in the Hijaz and the capital of Makkah province in Saudi Arabia. The city is located inland from Jeddah in a narrow valley at a height of above sea level...
(the Qibla
Qibla
The Qiblah , also transliterated as Qibla, Kiblah or Kibla, is the direction that should be faced when a Muslim prays during salah...
) for all latitudes and longitudes for all the Muslim countries of the 14th century. Knowledge of the direction of the Qibla is essential in Islam because Muslims pray in the direction of Mecca. The values present in al-Khalili’s tables have been determined to be amazingly accurate – indeed they have been calculated to be accurate up to three or four significant decimal digits. Up to the present time, it is not known how exactly al-Khalili went about calculating each of his entries.
Further reading
- Denis Roegel: An Extension of Al-Khalīlī's Qibla Table to the Entire World, 2008, INRIA technical report inria-00336090 (available on http://locomat.loria.fr)