Famous Scienitst Al - Battani

Al-Battani is otherwise called as Albategnius, Albategni or Albatenius in Lain. He was an Arab astronomer, astrologer, and mathematician. He introduced a number of trigonometric relations, and his Kitāb az-Zīj was frequently quoted by many medieval astronomers, including Copernicus.

He was born in Harran near Urfa, in syria Upper Mesopotamia, which is now in Turkey, and his father was a famous maker of scientific instruments. His epithet aṣ-Ṣabi’ suggests that among his ancestry were members of the Sabian sect; however, his full name indicates that he was Muslim. Some western historians state that he is of noble origin, like an Arab prince, but traditional Arabic biographers make no mention of this. He lived and worked in ar-Raqqah, a city in north central Syria.

He was able to correct some of Ptolemy's results and compiled new tables of the Sun and Moon, long accepted as authoritative. Some of his measurements were even more accurate than ones taken by Copernicus many centuries later. Researchers have ascribed this phenomenon to al-Battānī being in a geographical location that is closer to the southern latitude, which might have been more favorable for such observations.

Al-Battānī discovered that the direction of the Sun's apogee, as recorded by Ptolemy, was changing.(In modern heliocentric terms this is due to the changing direction of the eccentricity vector of the Earth's orbit). He also introduced, probably independently of the 5th century Indian astronomer Aryabhata, the use of sines in calculation, and partially that of tangents. He also calculated the values for the precession of the equinoxes (54.5" per year, or 1° in 66 years) and the obliquity of the ecliptic (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.

Al-Battānī's work is considered instrumental in the development of science and astronomy. Copernicus quoted him in the book that initiated the Copernican Revolution, the De Revolutionibus Orbium Coelestium. Al-Battānī was frequently quoted by Tycho Brahe, Riccioli, among others. Kepler and Galileo showed interest in some of his observations, and his data continues to be used in geophysics.

The main achievements of al-Battani’s are:

• He cataloged 489 stars.

• He refined the existing values for the length of the year, which he gave as 365 days 5 hours 46 minutes 24 seconds, and of the seasons.

• He calculated 54.5″ per year for the precession of the equinoxes and obtained the value of 23° 35′ for the inclination of the ecliptic.

Al-Battani passed away in 317 H. /929 A.D., near the city of Moussul in Iraq.