Ibn al-Shatir
Ibn al-Shatir | |
---|---|
Born | 1304 |
Died | 1375 (aged 71) |
Occupation | Astronomer |
Works | kitab nihayat al-sul fi tashih al-usul |
ʿAbu al-Ḥasan Alāʾ al‐Dīn bin Alī bin Ibrāhīm bin Muhammad bin al-Matam al-Ansari
Biography
Ibn al-Shatir was born in Damascus, Syria around the year 1304. His father died when he was six years old. His grandfather took him in which resulted in Ibn al-Shatir learning the craft of inlaying ivory.[2] Ibn al-Shatir traveled to Cairo and Alexandria to study astronomy, where he fell in, inspired him.[2] After completing his studies with Abu ‘Ali al-Marrakushi, Ibn al-Shatir returned to his home in Damascus where he was then appointed muwaqqit (timekeeper) of the Umayyad Mosque.[2] Part of his duties as muqaqqit involved keeping track of the times of the five daily prayers and when the month of Ramadan would begin and end.[3] To accomplish this, he created a variety of astronomical instruments. He made several astronomical observations and calculations both for the purposes of the mosque, and to fuel his later research. These observations and calculations were organized in a series of astronomical tables.[4] His first set of tables, which have been lost over time, allegedly combined his observations with those of Ptolemy, and contained entries on the Sun, Moon and Earth.[3]
Astronomy
Ibn al-Shatir′s most important astronomical treatise was kitab nihayat al-sul fi tashih al-usul ("The Final Quest Concerning the Rectification of Principles"). In it he refined the
Drawing on the observation that the distance to the Moon did not change as drastically as required by Ptolemy's lunar model, Ibn al-Shatir produced a new lunar model that replaced Ptolemy's crank mechanism with a double epicycle model that computed a more accurate range of distances of the Moon from the Earth.[5]
Solar Model
Ibn al-Shatir's Solar Model exemplifies his commitment towards accurate observational data, and its creation serves as a general improvement towards the Ptolemaic model. When observing the Ptolemaic solar model, it is clear that most of the observations are not accounted for, and cannot accommodate the observed variations of the apparent size of the solar diameter.[6] Because the Ptolemaic system contains some faulty numerical values for its observations, the actual geocentric distance of the Sun had been greatly underestimated in its solar model. And with the problems that had arisen from the Ptolemaic models, there was an influx of need to create solutions that would resolve them. Ibn al-Shatir's model aimed to do just that, creating a new eccentricity for the solar model. And with his numerous observations, Ibn al-Shatir was able to generate a new maximum solar equation (2;2,6°), which he found to have occurred at the mean longitude λ 97° or 263° from the apogee.[7] As the method was deciphered through geometric ways, it was easy to identify that 7;7 and 2;7 were the radii of the epicycles.[8] In addition, his final results for apparent size of the solar diameter were concluded to be at apogee (0;29,5), at perigee (0;36,55), and at mean distance (0;32.32).[7] This was partially done by reducing Ptolemy’s circular geometric models to numerical tables in order to perform independent calculations to find the longitude of the planets.[1] The longitude of the planets was defined as a function of the mean longitude and the anomaly. Rather than calculating every possible value, which would be difficult and labor-intensive, four functions of a single value were calculated for each planet and combined to calculate quite accurately the true longitude of each planet.[9]
To calculate the true longitude of the moon, Ibn al-Shatir assigned two variables, η, which represented the Moon's mean elongation from the Sun, and γ, which represented its mean anomaly. To any pair of these values was a corresponding e, or equation which was added to the mean longitude to calculate the true longitude. Ibn al-Shatir used the same mathematical scheme when finding the true longitudes of the planets, except for the planets the variables became α, the mean longitude measured from apogee (or the mean center) and γ which was the mean anomaly as for the moon. A correcting function c3' was tabulated and added to the mean anomaly γ to determine the true anomaly γ'.[9] As shown in Shatir's model, it was later discovered that Shatir's lunar model had a very similar concept as Copernicus.[2] Ibn al-Shatir never gave motivation towards his two epicycles to be adopted, so it was hard to tell the difference between his model and the Ptolemaic model.
Possible influence on Nicolaus Copernicus
Although Ibn al-Shatir's system was firmly geocentric (he had eliminated the Ptolemaic eccentrics), the mathematical details of his system were identical to those in
Instruments
The idea of using hours of equal time length throughout the year was the innovation of Ibn al-Shatir in 1371, based on earlier developments in
Ibn al-Shatir also invented a
See also
- List of Arab scientists and scholars
- Islamic scholars
Notes
- ^ S2CID 143576999.
- ^ ISBN 978-1784531386.
- ^ OCLC 772844807.
- ^ S2CID 121312064.
- broken anchor], volume 3 at pages 1108–1109.
- S2CID 115311028.
- ^ S2CID 120033970.
- ^ Roberts, Victor. "The Solar and Lunar Theory of Ibn ash-Shāṭir: A Pre-Copernican Copernican Model" (PDF). Chicago Journals. 48: 428–432 – via JSTOR.
- ^ a b Abbud, Fuad (1962). "The Planetary Theory of Ibn al-Shatir: Reduction of the Geometric Models to Numerical Tables". The University of Chicago Press. 53: 492–499 – via JSTOR.
- ^ a b c Berggren, J (1999). "Sundials in medieval Islamic science and civilization" (PDF). Coordinates.
- JSTOR 986461.
- ^ ISBN 978-0-387-31022-0. (PDF version)
- .
- ^ Roberts, Victor (1966). "The Planetary Theory of Ibn al-Shatir: Latitudes of the Planets". The University of Chicago. 57: 208–219 – via JSTOR.
- ^ a b "History of the sundial". National Maritime Museum. Archived from the original on 2007-10-10. Retrieved 2008-07-02.
- ^ Jones 2005.
- ^ (King 1983, pp. 547–8)
- ^ a b c d Rezvani, Pouyan. "The Role of ʿIlm al-Mīqāt in the Progress of Making Sundials in the Islamic Civilization" (PDF). Academia. Archived from the original (PDF) on 2021-12-19. Retrieved 2021-12-19.
- ^ S2CID 144315162.
References
- Fernini, Ilias. A Bibliography of Scholars in Medieval Islam. Abu Dhabi (UAE) Cultural Foundation, 1998
- Jones, Lawrence (December 2005). "The Sundial And Geometry". North American Sundial Society. 12 (4).
- Kennedy, Edward S. (1966) "Late Medieval Planetary Theory." Isis 57:365–378.
- Kennedy, Edward S. and Ghanem, Imad. (1976) The Life and Work of Ibn al-Shatir, an Arab Astronomer of the Fourteenth Century, History of Arabic Science Institute, University of Aleppo.
- Linton, Chris. From Eudoxus to Einstein: A History of Mathematical Astronomy. Cambridge University Press, Cambridge, 2004, ISBN 978-0-521-82750-8.
- Roberts, Victor. "The Solar and Lunar Theory of Ibn ash-Shatir: A Pre-Copernican Copernican Model". Isis, 48(1957):428–432.
- Roberts, Victor and Edward S. Kennedy. "The Planetary Theory of Ibn al-Shatir". Isis, 50(1959):227–235.
- Saliba, George. "Theory and Observation in Islamic Astronomy: The Work of Ibn al-Shatir of Damascus". Journal for the History of Astronomy, 18(1987):35–43.
- Turner, Howard R. Science in Medieval Islam, an illustrated introduction. University of Texas Press, Austin, 1995. ISBN 0-292-78147-4(hc)
- ISBN 978-0-8147-8023-7
Further reading
- King, David A. (2007). "Ibn al-Shāṭir: ʿAlāʾ al-Dīn ʿAlī ibn Ibrāhīm". In Thomas Hockey; et al. (eds.). The Biographical Encyclopedia of Astronomers. New York: Springer. pp. 569–70. ISBN 978-0-387-31022-0. (PDF version)
External links
- Science in Medieval Islam by Howard R. Turner
- The Lights of the Stars