Al-Battani

Al-Battani "Albategnius" , son of Jabir ibn Sinan al-Harrani who had a notable reputation as an instrument maker in Harran. The name makes the identification certain that al-Battani himself was professional in making of astronomical instruments and there is a good indication that he learn these skills from his father.

Al-Battani is one of the most popular observers and a leader in geometry, theoretical and practical astronomy, and astrology. He composed work on astronomy, with tables, containing his own observations of the sun and moon and an exact description of their motions than that given in Ptolemy’s “Almagest”.

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.

Rather than using geometrical methods, as other scientists had done, Al-Battani used trigonometric methods which were the major improvement. Al-Battani showed that the farthest distance of the Sun from the Earth varies and, as a result, annular eclipses of the Sun are possible as well as total eclipses. Al-Battani is important in the development of science for a number of reasons, but one of these must be the large influence his work had on scientists such as Tycho Brahe, Kepler, Galileo and Copernicus.

Historians all agree that Al-Battani passed away in 317 H./929 A.D., near the city of Moussul in Iraq. He was regarded as one of the most famous Arab astronomers. He dedicated all his life until his death to the observation of planets and stars.