The impact of Al-Battani on European Astronomy

Al-Battani used the widest variety of instruments: astrolabes, tubes, a gnomon divided into twelve parts, a celestial globe with five armillaries, parallax rules, a mural quadrant, sundials, vertical as well as horizontal.

Astronomical observation in Islamic times reached beyond what much of scholarship gives it credit for. Many aspects of it were pioneering as can be observed from few extracts on the life and works of al-Battani by Carra de Vaux. The merit of al-Battani, the De Vaux points out, is to pioneer the use of trigonometry in his operations. Al-Battani is also quoted saying:

`after having lengthily applied myself in the study of this science, I have noticed that the works on the movements of the planets differed consistently with each other, and that many authors made errors in the manner of undertaking their observation, and establishing their rules. I also noticed that with time, the position of the planets changed according to recent and older observations; changes caused by the obliquity of the ecliptic, affecting the calculation of the years and that of eclipses. Continuous focus on these things drove me to perfect and confirm such a science.’ Al-Battani

More crucially, al-Battani, explained his mathematical operations and urged others `to continue observation, and to search,’ in order to perfect and expand his work. He said that it was no impossibility that with the passing of time, more would be found, just as he himself expanded and added on the work of his predecessors. `Such is the majesty of celestial science, so vast, that none could ever encompass its study by himself.’

Al-Battani also used the widest variety of instruments: astrolabes, tubes, a gnomon divided into twelve parts, a celestial globe with five armillaries, of which, likely, he was the author, parallax rules, a mural quadrant, sundials, vertical as well as horizontal. And, understandably, he opted for the largest instruments; the measures taken by the parallax rules relate to a circle of no less than five meters in diameter; and the quadrant was no less than one meter.

So great was al-Battani’s impact, De Vaux observes, that subsequent observation bore his mantel. Thus, Jewish scientists, Ibn Ezra, Maimonides, Levi Ben Gerson, and others, who through the centuries scattered Islamic learning in all regions of Europe, made al-Battani’s calculations the foundations of theirs. Amongst the Christians, Robertus Cestrensis (Retinensis) devised tables of the celestial movements for the meridian of London for the year 1150 after him. Albertus Magnus, Alphonso X, Regiomontanus, Nicolas Cusanus, Copernicus, and Tycho Brahe are amongst others, on whom, al-Battani, in one way or another impacted. It was left to Nallino, who most recently edited al-Battani’s work in Arabic with a Latin translation.