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Al-Battānī
A modern artist's impression of al-Battānī holding an astrolabe
Born	c. 858 CE Harran, Bilad al-Sham
Died	929 CE Qasr al-Jiss, near Samarra
Residence	Abbasid Caliphate
Academic background
Influences	Ptolemy
Academic work
Era	Islamic Golden Age
Main interests	Mathematics, Astronomy, Astrology
Notable works	Kitāb az-Zīj
Notable ideas	Trigonometrical relationships
Influenced	Abū al-Wafā', al-Bīrūnī, Copernicus

Abū ʿAbd Allāh Muḥammad ibn Jābir ibn Sinān al-Raqqī al-Ḥarrānī aṣ-Ṣābiʾ al-Battānī (Arabic: محمد بن جابر بن سنان البتاني‎) (Latinized as Albategnius, Albategni or Albatenius) (c. 858 – 929) was an Arab^[1][2][3]astronomer, astrologer, and mathematician. He introduced a number of trigonometric relations, and his Kitāb az-Zīj was frequently quoted by many medieval astronomers, including Copernicus.^[4]

Al-Battani is sometimes referred to as the "Ptolemy of the Arabs",^[5] and is widely considered the greatest and best known astronomer of the medieval Islamic world.^[6][7][8][9]

Life

Little is known about al-Battānī's life beside that he was born in Harran near Urfa, in Upper Mesopotamia, which is now in Turkey, and his father was a famous maker of scientific instruments.^[4] His epithet aṣ-Ṣabi’ suggests that among his ancestry were members of the Sabian sect; however, his full name indicates that he was Muslim.^[10] Some western historians state that he is of noble origin, like an Arab prince,^[11] but traditional Arabic biographers make no mention of this.^[4] He lived and worked in Raqqa, a city in north central Syria.

Astronomy

One of al-Battānī's best-known achievements in astronomy was the determination of the solar year as being 365 days, 5 hours, 46 minutes and 24 seconds which is only 2 minutes and 22 seconds off.^[10]

He was able to correct some of Ptolemy's results and compiled new tables of the Sun and Moon, long accepted as authoritative.^[11] Some of his measurements were even more accurate than ones taken by Copernicus many centuries later. Researchers have ascribed this phenomenon to al-Battānī's location lying closer to the equator so that the ecliptic and the Sun were higher in the sky and therefore less susceptible to atmospheric refraction.^[10]

Al-Battānī discovered that the direction of the Sun's apogee, as recorded by Ptolemy, was changing.^[12] (In modern heliocentric terms this is due to the changing direction of the eccentricity vector of the Earth's orbit). He also introduced, probably independently of the 5th century Indian astronomer Aryabhata, the use of sines in calculation, and partially that of tangents.^[11] He also calculated the values for the precession of the equinoxes (54.5" per year, or 1° in 66 years) and the obliquity of the ecliptic (23° 35').^[10] He used a uniform rate for precession in his tables, choosing not to adopt the theory of trepidation attributed to his colleague Thabit ibn Qurra.

Al-Battānī's work is considered instrumental in the development of science and astronomy.^[10]Copernicus quoted him in the book that initiated the Copernican Revolution, the De Revolutionibus Orbium Coelestium, where his name is mentioned no fewer than 23 times,^[13] and also mentioned him in the Commentariolus.^[14] Al-Battānī was frequently quoted by Tycho Brahe and Riccioli, among others. Kepler and Galileo showed interest in some of his observations,^[4] and his data continues to be used in geophysics.^[15]

The major lunar crater Albategnius is named in his honor.^[16]

Mathematics

In mathematics, al-Battānī produced a number of trigonometrical relationships:

tan⁡a=sin⁡acos⁡adisplaystyle tan a=frac sin acos a

sec⁡a=1+tan2⁡adisplaystyle sec a=sqrt 1+tan ^2a

He also solved the equation sin x = a cos x discovering the formula:

sin⁡x=a1+a2displaystyle sin x=frac asqrt 1+a^2

He gives other trigonometric formulae for right-angled triangles such as:^[10]

bsin⁡(A)=asin⁡(90∘−A)displaystyle bsin(A)=asin(90^circ -A)

Al-Battānī used al-Marwazi's idea of tangents ("shadows") to develop equations for calculating tangents and cotangents, compiling tables of them. He also discovered the reciprocal functions of secant and cosecant, and produced the first table of cosecants, which he referred to as a "table of shadows" (in reference to the shadow of a gnomon), for each degree from 1° to 90°.^[17]

Works

Al-Battānī's major work is Kitāb az-Zīj ("Book of Astronomical Tables"). It was largely based on Ptolemy's theory, and other Greco-Syriac sources, while showing little Indian or Persian influence.^[4][18] In his zij, he provided descriptions of a quadrant instrument.^[19]

This book went through many translations to Latin and Spanish, including a Latin translation as De Motu Stellarum by Plato of Tivoli in 1116, which was later reprinted with annotations by Regiomontanus.^[11] A reprint appeared at Bologna in 1645. The original MS. is preserved at the Vatican; and the Escorial library possesses in MS. a treatise of some value by him on astronomical chronology.^[11]

In Popular Culture

A ship in Star Trek: Voyager is named after Al-Battānī, known as the USS Al-Batani, which Janeway originally served on.

See also

• List of Arab scientists and scholars


• Zij

Notes

References

• Al-Battānī sive Albatenii, Opus Astronomicum. Ad fidem codicis escurialensis arabice editum, ed. by Carlo Alfonso Nallino. Milan, Ulrico Hoepli, 1899-1907 [= Pubblicazioni del Reale Osservatorio di Brera in Milano, nr. XL], 412 + 450 + 288 pp. (anast.: I-III, [La Finestra editrice], Lavis 2002
  ISBN 978-8888097-26-8
  


• 
  Hartner, Willy (1970–80). "Al-Battānī, Abū ʿAbd Allāh Muḥammad Ibn Jābir Ibn Sinān al-Raqqī al-Ḥarrānī al–Ṣābi". Dictionary of Scientific Biography. New York: Charles Scribner's Sons. ISBN 0-684-10114-9.
  


• 
  O'Connor, John J.; Robertson, Edmund F., "Abu Abdallah Mohammad ibn Jabir Al-Battani", MacTutor History of Mathematics archive, University of St Andrews.

External links

• 
  Dalen, Benno van (2007). "Battānī: Abū ʿAbd Allāh Muḥammad ibn Jābir ibn Sinān al‐Battānī al‐Ḥarrānī al‐Ṣābiʾ". In Thomas Hockey; et al. The Biographical Encyclopedia of Astronomers. New York: Springer. pp. 101–3. ISBN 978-0-387-31022-0. (PDF version)


• 
  Weisstein, Eric Wolfgang (ed.). "Albategnius (ca. 858–929)". ScienceWorld.
  


• 
  Texts on Wikisource:
  
  • 
    Gilman, D. C.; Peck, H. T.; Colby, F. M., eds. (1905). "al-Battani, Mohammed ibn Jabir ibn Sinan". New International Encyclopedia (1st ed.). New York: Dodd, Mead.
    
  
  
  • 
    "Albategnius". Encyclopædia Britannica. 1 (11th ed.). 1911. p. 491.
    
  
  
  • 
    "al-Battani". New International Encyclopedia. 1920.