Battânî

Astronomer (Born Harran - Urfa ?, 858? – Death?, 929). He is one of the greatest astronomers of Islamic World. His real name is Ebû Abdillâh Muhammed b. Câbir b. Sinân er-Rakkî el-Harrânî. He is known as Albetanius, Albategnus or Albategni in the West. He is originally child of a Sabaic family and most probably was born in Battan near to Harran in the first half of the III. Century ( 9^th a.d.). That he was called “Harrani” also shows this. Another name of him “Rakki” which is only present in İbnü’n-Nedîm’s el – Fihrist comes from the city of Rakka which is located in the left shore of Euphrates and where he spent most of his life. There is limited information on his birth date and childhood. It is known that he made his first observations in the Islamic Year 264 (877 a.d.). If we assume that he was twenty years old at that time, it can be said that he was born in 244 (858 a.d.).

It is probable that Battânî’s father is the famous master of astronomy devices who is mentioned by İbnü’n-Nedîm, Câbir b. Sinân el-Harrânî. Battânî’s tag and skill in inventing and producing astronomy devices strengthen this probability. Information on the following stages of his life is very limited, too. İbnü’n-Nedîm’s el-Fihrist and İbnü’l-Kıftî’s Târihu’l-hükemâ state that he was one of the prominent scholars and observers in geometry, theoretical and practical astronomy and astrology; he gave tables about Ptolemy’s observations on sun and moon, edited and developed the knowledge in his el-Mecis-tî and wrote a star catalogue where he declared his new inventions; gave movements of five planets and astronomic calculations related to them in this book; made one part of the observations he mentioned in his catalogue in 267 (880) and 287 (900); according to his answers to the questions of Cafer b. Muktefi his observation works started in 264 (877) and lasted until 306 (918); besides he did his observations on constant stars in 299 (911).

The mentioned sources claim that he went to Baghdad with the Beni Zeyyat family from the people of Rakka upon an injustice they were exposed to and on his return to his homeland in 317 (929) he passed away in Kasrü’l-Cis which was built by the Caliph Mu’tasım. İbn Hallikân on the other hand claims that Battâni­’s death place was Hadr which is a city near to Mosul. The researcher Nallino on the contrary says that the word of Hadr is a mistype of Ciss. Considering that Yâkût el-Hamevî mentioned the same place as Kasrü’l-Hadr, it is understood that Nallino’s claim is coherent. It can be added to information on Battâni’s life that he observed a solar and a lunar eclipse in Antakya on the 23^rd of January and on the 2^nd of August 901. He mentions these observations in his own catalogue. Some of Battânî’s discoveries and successes are following:

1- He is the first scientist to use sinus instead of Greek beam. 2- He developed the concept of cotangent for the first time and created a graded table. 3- He determined the moon’s average movement at longitude. 4- He messed visible diameters of sun and moon. 5- He calculated changes observed on the sun during one year and on the moon during one month. 6- He developed a very stable method to calculate the degree of lunar eclipse. 7- He examined some problems of spherical trigonometry using orthographic projection method. 8- He analyzed right triangles, defined basic terms of geometry such as sinus, cosine, tangent, cotangent, secant and cosecant and used them for the first time in real terms. 9- He is the first scientist to prepare the astronomic table. 10- He calculated trigonometric values of angles from zero to ninety degrees. 11- He applied solution methods of algebra to trigonometric equations. 12- All mathematic and trigonometric techniques mentioned above were also used by scientists such as Copernicus, Kepler, Tycho Brahe and Galilei between the 15^th and 17^th centuries in Western Europe.

WORKS:

Kitâbü’z-Zîc (Battânî states that he developed current theories and deductions by basing on new observations. In the first chapters of this work which consists of fifty-seven chapters, practical definitions were given and problems determined. This work which played a very great role at the development of astronomy and spherical trigonometry was granted the importance it deserved three centuries later in the West and this work was translated to Latin by Robertus Retinensis and Plato Tibastinus in 12^th century and later to other languages..), Kitâb ü Mârifeti’l-Metâlii’l-Bürûc fî mâ Beyne Erbaati’l-Felek (In this work about astronomy birth points of 12 stars, birth places of moon and stars and lunar eclipse were mentioned.), Risâletü’n fi Tahkik-i Akdari’l-İttisalat (In this work which is about measurements of the distance of stars, stars as light sources were explained using latitudes and spherical trigonometry.), Risâletü’n fi Ameliyyati’t-Tercimi’d-Dakika, Kitab u Ta’dili’l-Kevakib, İlmü’n-Nücûm, Kitabü’n fi İlmi’l-Felek, Kitabün an Daireti’l-Bürüc ve’l-Kubbeti’ş- Şemsiye, Muhtasarun Ii Kütübi Batlemyüsi’l-Felekiyye, Risâletü’n fi Mikdari’l İttisalati’l-Felekiyye.