Major Works of Al-Battani
Mohammed ibn Jabir ibn Sinan Al-Harrani, known as Al-Battani or Abu Abdullah, was born in the city of Harran in the Levant in 858 CE. He is renowned as one of the most significant Muslim scholars in the fields of astronomy and mathematics, making notable contributions that impacted both the Islamic and Western worlds.
Following his death, Al-Battani’s works and knowledge gained widespread recognition, particularly influencing the European Renaissance. Notably, the Vatican still houses many of his original manuscripts. His writings have served as crucial references in astronomy and mathematics, with some of his most important works listed below:
The Zīj of Al-Sabī
The Zīj of Al-Sabī stands as one of Al-Battani’s most significant contributions. In this work, he consolidates all his astronomical findings based on his extensive study of celestial movements. He critically evaluated existing texts that described star motions, which often contained errors due to reliance on outdated observational methods. In this book, he either built upon or corrected these concepts where necessary.
In the Zīj of Al-Sabī, Al-Battani addresses several key topics, including:
- The relationship between the ecliptic and the celestial equator.
- The calculation of the durations of years, seasons, eclipses, and their timings, based on Ptolemy’s work in the “Almagest,” while also identifying errors in traditional calculations through geometric and numerical proofs.
- The derivation of planetary movements through tables calibrated to local noon as per the timekeeping in the city of Raqqa, where Al-Battani lived and grew up.
Other Notable Works
Al-Battani authored numerous other books and treatises, among which the most notable include:
- The work titled “Ma’arifat Mata’al Al-Buruj Fi Ma Baina Arba’ Al-Falak,” which offers mathematical solutions to astrological problems related to the observer’s position.
- Two treatises, “Risalat Fi Tahqiq Aqdaar Al-Ittisal” and “Risalat Fi Maqdar Al-Ittisal,” which detail the conjunction of planets in terms of longitude and latitude.
- The treatise “Sharh Al-Maqalat Al-Arba’a Li-Btolemaios,” which elaborates on Ptolemy’s final conclusions in his “Almagest,” addressing astrological problems and their implications for worldly affairs.
- The book “Tad’il Al-Kawakib,” where Al-Battani distinguished between the fixed paths of planets and their apparent movements, which vary based on their positions.
Scientific Contributions of Al-Battani
Al-Battani made numerous scientific contributions across various fields, with the following being the most significant:
Contributions in Astronomy
Al-Battani excelled particularly in astronomy, with key contributions including:
- Correction of planetary observations regarding their motion and alignment, as well as cataloging 489 stars in the Zīj of Al-Sabī.
- Accurate estimation of the length of the solar year, defined as 365 days, 5 hours, 46 minutes, and 24 seconds. He also specified the timing of seasons and months, alongside studying the variations in day and night durations.
- Thorough examination of the sun and moon’s movements, allowing precise predictions of eclipses.
- Calculation of the sun’s axial tilt, which he approximated to be 23 degrees, along with determining the solar equinox.
- Identification of the sun’s apogee (farthest point from Earth), demonstrating the feasibility of both total and annular lunar eclipses, as well as partial solar eclipses.
- He was the first to discover the points of zenith and nadir.
- Identification of solar aphelion and variations in the solar orbit and its inclination.
Contributions in Mathematics
Al-Battani enhanced Ptolemy’s astronomical calculations through a mathematical approach, utilizing trigonometry instead of traditional geometric methods. He employed right-angled triangles, developed values in spherical trigonometry, and created tables using sine and cosine functions, thus significantly advancing the field of trigonometry.