“The Fourth Part of the World: The Race to the Ends of the Earth, and the Epic Story of the Map That Gave America Its Name” (Toby Lester)

Since his name came up in a book I’m reading12 called The Fourth Part of the World

Abu Abdallah Muhammad ibn Jabir ibn Sinan ar-Raqqi al-Harrani as-Sabi al-Batani (Arabic محمد بن جابر بن سنان البتاني `Abū `Abd Allāh Muḥammad ibn Jābir ibn Sinān ar-Raqqī al-Ḥarrānī aṣ-Ṣābi` al-Battānī c. 858, Harran – 929, Qasr al-Jiss, near Samarra) Latinized as Albategnius, Albategni or Albatenius was an Arab astronomer, astrologer, and mathematician, born in Harran near Urfa, which is now in Turkey. His epithet as-Sabi suggests that among his ancestry were members of the Sabian sect; however, his full name affirms that he was Muslim.

One of his best-known achievements in astronomy was the determination of the solar year as being 365 days, 5 hours, 46 minutes and 24 seconds.
His work, the Zij influenced great European astronomers like Tycho Brahe, Johannes Kepler, etc. Nicholas Copernicus repeated what Al-Battani wrote nearly 700 years before him as the Zij was translated into Latin thrice.
The modern world has paid him homage and named a region of the moon Albategnius after him.

Al Battani worked in Syria, at ar-Raqqah and at Damascus, where he died. He was able to correct some of Ptolemy’s results and compiled new tables of the Sun and Moon, long accepted as authoritative, discovered the movement of the Sun’s apogee, treated the division of the celestial sphere, and introduced, probably independently of the 5th century Indian astronomer Aryabhata, the use of sines in calculation, and partially that of tangents, forming the basis of modern trigonometry. He also calculated the values for the precession of the equinoxes (54.5″ per year, or 1° in 66 years) and the inclination of Earth’s axis (23° 35′). 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.

His most important work is his zij, or set of astronomical tables, known as al-Zīj al-Sābī with 57 chapters, which by way of Latin translation as De Motu Stellarum by Plato Tiburtinus (Plato of Tivoli) in 1116 (printed 1537 by Melanchthon, annotated by Regiomontanus), had great influence on European astronomy. The zij is based on Ptolemy’s theory, showing little Indian influence. A reprint appeared at Bologna in 1645. Plato’s original manuscript is preserved at the Vatican; and the Escorial Library possesses in manuscript a treatise by Al Battani on astronomical chronology.

[Click to continue reading Muhammad ibn Jābir al-Harrānī al-Battānī – Wikipedia, the free encyclopedia]

Al-Battani’s book, On the Science of the Stars, apparently discusses

the system proposed by Bartholomeus and confirmed by the ancients, in which the places and regions of the world are noted according to latitude and longitude.

  1. on my iPad, if you are curious []
  2. thanks to a tip by phule []

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