Al-Battani (Albategnius)

Known for

Very accurate measurement of the solar year; use of trigonometry in astronomy

Biography

Astronomer from Harran who made observations for over 40 years at Raqqa on the Euphrates.

Contributions

• Measured the solar year as 365 days, 5 hours, 46 minutes and 24 seconds
• Improved values for the precession of the equinoxes and the tilt of the Earth's axis
• Used sines and cotangents instead of Greek chord methods

Major works

• Kitab al-Zij (Zij al-Sabi)