Medieval Islamic Astronomy (130/ /1750)

Transcription

1 1 Medieval Islamic Astronomy (130/ /1750) Jan P. Hogendijk Dept of Mathematics, Utrecht /KFUPM May 12, 2011

2 2 Summary of this lecture 1. The sources of medieval Islamic astronomy. 2. Rough outline of the development of medieval Islamic astronomy. 3. Three examples of sources. 4. The universe of the orthodox Islamic theologians.

3 3 Extant sources on medieval Islamic astronomy I 1. More than 100 Zījes: handbook with tables and instructions. Typically 40 pages of instructions ((250 words per page), 150 pages tables. Surveys: [Kennedy 1956], [King, Samso, Goldstein, 2001]. Computer analysis by Benno van Dalen, Frankfurt am Main. 2. Ca ? shorter or longer treatises by astronomers (text, no tables). Surveys: [Sezgin 1978, Rosenfeld and Ihsanoglu 2003]

4 4 Extant sources on medieval Islamic astronomy II 3. Ca instruments (astrolabes, quadrants, others). 4. Observatories: ruins (Samarkand, Maragha); Jai Singh s observatories in Delhi and Jaipur are extant. See [Sayili 1960]. Preliminary catalogue of astrolabes by David King on the internet. Many instruments rebuilt in Frankfurt, Institute for History of Arabic-Islamic Science, see F. Sezgin, Science and Technology in Islam, Frankfurt 2010, accessible through via English, Publications.

5 5 Cultural Context Development of astronomy stimulated by large-scape patronage by caliphs and rulers. Applications: Prediction of astronomical phaenomena, including lunar and solar eclipses, first visibility of the lunar crescent. Mathematical geography was part of astronomy. Timekeeping also. Problems inspired by Islam: direction of Makka, prayer tables. Astronomy was also applied in astrological predictions. There was much disagreement on the value of astrology.

6 6 Historical Survey I Early Muslims were already interested in astronomy. see [Heinen 1982] 130/ /900, Baghdad, Iraq: Assimilation from pre-islamic Iran, India, Greek; Translations into Arabic (most important work: the Almagest of Ptolemy, ca. 150 CE.)

7 7 Historical Survey II ca. 200/820: Eastern Islamic world: Beginning of (programs) of observations to check and adjust the system of Ptolemy (ca. 150 CE). Primarily earth radius and solar theory. ca. 4th/10th centuries: Advances in mathematics (spherical trigonometry etc.), and in observational instruments. ca. 400/ /1400. Eastern Islamic world: Replacement of some non-aristotelian features of Ptolemy s models by philosophically acceptable alternatives.

8 8 Three sources I 1. Early period: Al-Battānī (Syria, died 317/929), Zīj (Astronomical Handbook). Published in [Nallino ], Arabic text and modern Latin translation. Ca. 227 pages Arabic text, plus 180 pages numerical tables. Purpose: Prediction of astronomical phenomena: positions of sun, moon, planets; lunar and solar eclipses; first and last visibility of moon and planets. Innovations: Computations for the solar orbit.

9 9 Three sources II 2. Abu l-rayḥān al-bīrūnī (Iran/Turkm/Uzb/Afghanistan, died 440/1048) al-qānūn al-mas c ūdī, in 11 Books, ca pages text, 250 pages tables. Perhaps the most brilliant work of Islamic astronomy. Purpose: Theoretical exposition with all proofs. Arabic text published in unreliable edition. Table of contents in English [Kennedy 1971]. Uncritical Russian translation: NEVER translated into a European language. Al-Bīrūnī wrote much more: also Kitāb al-tafhīm fī Awā il Ṣinā c at al-tanjīm, Introduction to the First Principles of Astronomy; still the best introduction to the field. Available in facsimile with English translation [Ramsay Wright 1934].

10 10 What was in the 11 Books of al-qānūn al-mas c ūdī? 1. Fundamental cosmological principles; days, years. 2. Chronology and calendars 3. Plane Trigonometry, computation of tables, linear and quadratic interpolation 4. Spherical Trigonometry 5. Geodesy and mathematical geography 6. Time differences between different localities on earth, solar theory, equation of time 7. Lunar motion 8. Eclipses, lunar visibility 9. Fixed stars 10. Planets 11. Astrological computations

11 11 Example from Book I: Is the earth at rest or does it rotate? Al-Bīrūnī says that there were distinguished astronomers in his time who believed in the rotation of the Earth. He then decides between the values of the earth radius by the Greeks (ca km) and the Indians (double) by measuring the depression of the horizon from a mountain in Pakistan. He computes the velocity of our motion due to a rotating earth as one mile per breath (4 seconds) and says that such a motion must have an effect on the things we see. Conclusion: The earth is at rest.

12 12 Three sources III Naṣīr al-dīn al-ṭūsī (Iran, Iraq, died 672/1274) Al-Tadhkira fī c ilm al-hay a / Memoir on the Science of Cosmology Philosophical introduction on the structure of the cosmos (including the earth), 125 pages of text, no tables. Modifications of the Ptolemaic models of the universe. Arabic text with English translation [Ragep 1993].

13 Models of the universe: Ptolemy Outermost sphere (signs of zodiac) Sphere of the fixed stars Sphere of Saturn Sphere of Jupiter Sat Sphere of Mars Jup V Mo E Sun Me 13

14 New values of the obliquity of the ecliptic: Ptolemy: 23 o 51, o 14 Islamic modifications in the solar motion Solar motion: E earth, S sun. C center of orbit of sun. Apogee A C E Ptolemy: A fixed, in 5 Gemini, CE:CA=1:24 3th/9th c. Islamic astronomers: CE:CA approx. 1:30 (different values) Al Battani: A moves slowly S

15 15 Ptolemy s equant model P sun C E M Eq Mars, Jupiter, Saturn acc. to Ptolemy E=earth; center C of epicycle moves on circle with center M, motion is uniform with respect to Eq. Line C P (Planet) is parallel to line Earth mean sun.

16 16 Al-Tusi s modification sun P L C K E Eq Al Tusi: K moves uniformly around Eq; KL and LC move uniformly (so C has a sinusoidal motion on EqK)

17 17 Al-Tusi s couple of circles 2ω L ω K ω C Eq ω Al Tusi s Principle of Sinusoidal Motion

18 18 The universe of the Islamic theologians The model of the universe used by Islamic astronomers differed from the model of the universe used by the Islamic theologians, especially after the 11th century. Basis of the theological model: Koran, Ḥadīth (traditional reports about sayings of the Prophet Mohammad)

19 19 The universe of the theologians The earth is flat, and that Heavens and Hells are layers above / below it. Above the Earth, there are seven Heavens, below it, there are seven Hells. God s Throne is located above the seven Heavens. To this model, traditional (folklore) elements are added (a fish supporting the whole cosmos, etc.)

20 20 Literature and exam problems Literature: Steele, Ch. on Islamic astronomy, pp , (you don t have to memorize any Arabic names!) Exam problem: 1. see next presentation (about the theory of the sun) 2. Describe the working of an astrolabe.

21 21 Further literature (not for exam) Anton Heinen, Islamic Cosmology. A study of as-suyutis al-hay a as-sunniya fi l-hay a as-sunniya with critical edition, translation and commentary. Beiruter Texte und Studien no. 27, Nallino, Carlo Alfonso [Ed.]: Al-Battânî (d. 929) sive Albatenii Opus Astronomicum. Ad fidem codicis escurialensis arabice editum. I-II. Latin translation and commentary. III. Arabic text. Rome, Milan Reprinted Frankfurt 1997, Islamic Mathematics and Astronomy Abu l-rayḥān al-bīrūnī, al-qānūnu l-mas c ūdī, An Encyclopaedia of Astronomical Sciences, Hyderabad (India): Osmania Oriental Publications Bureau, , 3 vols.

22 22 Further literature (not for exam) Aby Raǐchan Beryni ( ), Izbrannye Proizvedeniya, part 5, Kanun Mas yda, 2 vols. Translated by B.A. Rosenfeld and A. Akhmedov. Tashkent E.S. Kennedy, Al-Bīrūnī s Masudic Canon, Al-Abhāth 24, 1971, pp , reprinted in E.S. Kennedy, Colleagues and Students, Studies in the Islamic Exact Sciences, Beirut 1983, pp F.J. Ragep, Naṣīr al-dīn al-ṭūsī s Memoir on astronomy Al-Tadhkira fī c ilm al-hay a, New York: Springer 1993, 2 vols.

23 23 Further literature (not for exam) R. Ramsay Wright (trans.), The Book of Instruction in the Elements of the Art of Astrology by al-bīrūnī. London pp. Reprinted: Frankfurt 1998 (Islamic Mathematics and Astronomy. 29) E.S. Kennedy, A survey of Islamic Astronomical Tables, Philadelphia: American Philosophical Society, 1956.

24 24 Further literature (not for exam) D.A. King, J.Samso, B.Goldstein, Astronomical Handboks and Tables from the Islamic world ( ): an Interim Report, Suhayl: Journal for the History of the Exact and Natural Sciences in Islamic Civilization , pp B.A. Rosenfeld, E. Ihsanoglu, Mathematicians, Astronomers and Other Scholars of Islamic civilization and their works (7th-19th c.), Iatanbul: IRCICA, 2003.

25 25 Further literature (not for exam) Fuat Sezgin, Geschichte des arabischen Schrifttums, Band 6, Astronomie bis ca. 430 H. Leiden: Brill, Aydin Sayılı, The Observatory in Islam and its PLace in the General History of the Observatory, Ankara 1960, 427 pp., reprinted Frankfurt 1998 (Islamic Mathematics and Astronomy vol. 97).