From: Thomas Hockey et
al. (eds.). The Biographical Encyclopedia of
Astronomers, Springer Reference. New York: Springer, 2007, pp. 570-572 |
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Ibn Sīnā:
Abū ʿAlī al-Ḥusayn ibn ʿAbdallāh ibn Sīnā
Alternate names
Avicenna
Sīnā
Born Afshana (near Bukhārā, Uzbekistan), 980
Died Hamadhān, (Iran), 1037
Ibn Sīnā, also known as Avicenna, is renowned for his great works in philosophy and medicine. He was also interested in the mathematical sciences, and he dealt with a number of problems related to astronomy and cosmology that had an impact on later astronomical work in Islamic regions and in Europe.
Ibn Sīnā lived a full and colorful
life and left an autobiography that was completed by his associate Abū ʿUbayd al-Jūzjānī.
Here we emphasize his astronomical career. Ibn Sīnā lived in Bukhārā
between 985 and 1005 where he studied Ptolemy’s Almagest at
an early age, basically being self-taught. It is said that he had access to
the library of Nūḥ
ibn Manṣūr (died: 997), which included many
books by the “Ancients.” Ibn Sīnā
lived in Gurganj from 1005 to 1012 where he wrote
Station of the Earth. He then resided in Jurjān
(1012–1014), and during that brief period he wrote his Comprehensive Observations,
a treatise on the Correction of the Longitude of Jurjān, and his Summary of the Almagest (which
he probably later incorporated into al-Shifāʾ, his
great philosophical encyclopedic work). It was here
that Jūzjānī began studying the Almagest
with him. In 1014–1015, Ibn Sīnā
moved to Rayy and then on to Hamadhān
(1015–1024), where he wrote several parts of the Shifāʾ. He
lived his final years in Iṣfahān,
where he completed the final parts of the Shifāʾ, including
the Almagest, composed the Najāt
(the abridgement of the Shifāʾ that
included logic, natural philosophy, and theology), and wrote his treatise
on Astronomical Instruments during periods of observation for the ruler
ʿAlāʾ al-Dawla. After Ibn Sīnā’s death, Jūzjānī
added supplemental treatises on astronomy and mathematics to his Najāt.
There are many astronomical works
associated with Ibn Sīnā,
but nine can be identified as authentic, and these can be classified into four
general categories: summaries of Ptolemy’s Almagest, works on
instruments and observational astronomy, philosophical and cosmological works,
and miscellaneous works.
(1) |
Ibn Sīnā’s Taḥrīr
al-majisṭī
is an extensive summary of the Almagest. Composed in Jurjān between 1012 and 1014, he later revised it,
and it became Part 4 of the mathematical section of the Shifāʾ.
Two works of Ibn Sīnā
that are often treated as separate treatises but are really part of the above
work are:
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(2) |
Ibn Sīnā’s al-Arṣād
al-kulliyya (Comprehensive observations) was
written in Jurjān (between 1012 and 1014) for Abū Muḥammad al-Shīrāzī and incorporated by Jūzjānī into Ibn
Sīnā’s Najāt
after his death. This short work contains nine chapters and was translated
into Persian as Raṣadhā
kullī in the Dānishnāmah-i
ʿilāʾī. Ibn Sīnā
states that he wishes to “abridge the explication of the comprehensive
observations from which one learns the general principles regarding the
configuration of the orb and the calculation of the motions.” |
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(3) |
Ibn Sīna wrote Maqāla
fī al-ālāt
al-raṣadiyya (Treatise on astronomical instruments) in Iṣfahān
sometime between 1024 and 1037, during his period of observations for ʿAlāʾ al-Dawla. This work indicates a practical side to Ibn Sīnā’s
astronomical interests and also demonstrates his interest in precision. |
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(4) |
Fīṭūl Jurjān ([Correction of the] longitude of Jurjān)
was written in Jurjān (1012–1014) and
dedicated to Zarrayn Kīs,
daughter of Amīr Qābūs
(= Shams al-Maʿālī). It is not extant
but is discussed by Bīrūnī in
his Taḥdīd
al-amākin, disparaging Ibn
Sīnā’s abilities in practical astronomy. |
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(5) |
al-Samāʾ wa-ʾl-ʿālam (De caelo et mundo)
was written for Abū al-Ḥusayn Aḥmad al-Sahlī [Suhaylī?].
Most likely, this is what later became the chapter of the
same name in the Shifāʾ. |
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(6) |
Maqāla fī al-ajrām
al-samāwiyya (al-ʿulwiyya) (Treatise on the celestial bodies). Like (5), this work is
written from the perspective of cosmology/natural philosophy, not
mathematical astronomy. |
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(7) |
ʿIllat qiyām
al-arḍ
fī ḥayyizihā (fī wasaṭ al-samāʾ) (On the cause of the Earth’s remaining in its position [in the
middle of the heavens] = Station of the Earth). It was written in Gurganj (circa 1005–1012), and dedicated to al-Sahlī to whom al-Samāʾ wa-ʾl-ʿālam is also dedicated. |
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(8) |
Maqāla (Risāla) fī
ibṭāl
ʿilm (aḥkām)
al-nujūm (Essay on
the refutation of astrology) or Risāla
fī al-radd ʿalā al-munajjimīn (Treatise
replying to the astrologers). This treatise attacks astrology and, along with
his work on the categorization of the sciences, demonstrates Ibn Sīnā’s attempt to
demarcate astronomy from astrology. |
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(9) |
Maqāla fī khawāṣṣ khaṭṭ
al-istiwāʾ (Essay on the
characteristics of the Equator). This work is no longer extant but Ibn Sīnā’s position
that the equatorial region is the most temperate is known from his Canon
on Medicine and from his critics, which included Bīrūnī,
Fakhr al-Dīn al-Rāzī, and Naṣīr al-Dīn al-Ṭūsī. |
Some of the works associated with Ibn Sīnā are misattributions, uncertain works, or duplications (due to longer or slightly different titles). (For details, see Ragep and Ragep.)
Ibn Sīnā’s astronomical knowledge and works may be viewed as less developed than those of his contemporaries such as Ibn al-Haytham and Bīrūnī; nevertheless, he had an impact upon later writers, and several general points can be made about his astronomical work.
First, Ibn Sīnā shows a remarkable interest in observational astronomy. Later writers refer to his observation of a Venus transit of the Sun, when it was seen as a mark on its face. This helped him establish that Venus was, at least sometimes, below the Sun. He also gave a new obliquity observation of 23;33,30° and provided a new longitude distance for Jurjān, from Baghdad, of 9;20° (compared with the traditional value of 8;0° and the modern value of 10;3°). Ibn Sīnā’s treatise on instruments includes a description of a large instrument with an improved sighting system that theoretically could provide considerably improved accuracy. Also, his summaries tend to emphasize the role of observation. Noteworthy as well are Ibn Sīnā’s criticisms of the poor instruments and observations of Ptolemy and Hipparchus.
Second, Ibn Sīnā’s cosmological writings are more within the tradition of natural philosophy rather than mathematical astronomy, and there is no extant work (and none reported) that one could call hayʾa work (i. e., one that provided a physical account of the mathematical models of the Almagest). One can therefore understand his concern with the dynamics of celestial motion and his reliance on natural philosophy to criticize Ptolemy’s attempt to rely strictly upon empirical evidence to disprove the possible rotation of the Earth. He is also aware of violations of the accepted physics in Ptolemy’s models as well as the need for reforming the Ptolemaic system and reconciling physics with mathematical astronomy.
Finally, Ibn Sīnā plays a significant role in redefining and recategorizing astronomy. He demarcates exact mathematical astronomy (ʿilm al-hayʾa) from astrology, which he views as being part of natural philosophy.