Al-Battani
البتاني
The Ptolemy of the Arabs
Born: ~858 CE, Harran (modern Turkey)
Died: 929 CE, Qasr al-Jiss, near Samarra (modern Iraq)
Also known as: Albategnius, Albatenius, Abu Abdullah Muhammad ibn Jabir al-Battani
Al-Battani was the most important astronomer of the medieval Islamic world, whose precise measurements refined Ptolemaic astronomy and influenced Copernicus. He accurately determined the length of the solar year, the obliquity of the ecliptic, and introduced the use of trigonometric functions into astronomy.
Key Accomplishments
- Determined the length of the solar year with extraordinary precision
- Introduced the systematic use of sine and cosine functions into astronomical calculations
- Corrected multiple values from Ptolemy's Almagest, including the obliquity of the ecliptic
- Authored "Kitab al-Zij al-Sabi," the most influential astronomical tables of the medieval period
- Directly influenced Copernicus, who cited him 23 times in "De Revolutionibus"
The Full Story
Abu Abdullah Muhammad ibn Jabir ibn Sinan al-Battani was born around 858 CE in Harran, in Upper Mesopotamia, into a family of Sabian background known for its astronomical tradition. He conducted the majority of his observations from his observatory at al-Raqqa, on the Euphrates in modern Syria, over a period of more than forty years.
Al-Battani's magnum opus, "Kitab al-Zij al-Sabi" (Astronomical Tables of the Sabian), was the most influential astronomical work between Ptolemy and Copernicus. Through painstaking observations, he determined the length of the solar year to be 365 days, 5 hours, 46 minutes, and 24 seconds, remarkably close to the modern value. He corrected Ptolemy's value for the obliquity of the ecliptic and the precession of the equinoxes, and he discovered the slow change in the eccentricity of the Earth's orbit (though he described it as the Sun's orbit).
Al-Battani's most enduring mathematical contribution was the systematic introduction of trigonometric functions, particularly the sine and cosine, into astronomical calculations, replacing the cumbersome chord functions used by Ptolemy. He also introduced the concept of cotangent and produced accurate trigonometric tables. These innovations made astronomical calculations significantly more efficient.
His work was translated into Latin in the 12th century by Plato of Tivoli as "De Motu Stellarum" and profoundly influenced European astronomers. Copernicus cited al-Battani by name no fewer than 23 times in "De Revolutionibus," and Tycho Brahe and Kepler also acknowledged his contributions. A lunar crater is named in his honor.
Places
Connected Figures
Thabit ibn Qurra
The Great Translator-Mathematician
Near-contemporary astronomer from the same region
The Golden AgeIbn Yunus
The Master Astronomer of Egypt
Later astronomer who built upon his observational tradition
The Golden AgeAl-Zarqali
The Inventor of the Universal Astrolabe
Later astronomer influenced by his astronomical tables
Notes
Sources
- [1]C.A. Nallino, "Al-Battani sive Albatenii Opus Astronomicum" (Milan, 1899-1907)
- [2]Willy Hartner, "Al-Battani," in Dictionary of Scientific Biography (Scribner's, 1970)
- [3]E.S. Kennedy, "A Survey of Islamic Astronomical Tables," Transactions of the American Philosophical Society, 1956