Ibn Al-Shatir

Ala Al-Din Abu'l-Hasan Ali Ibn Ibrahim Ibn al-Shatir (1304 – 1375) (Arabic: ابن الشاطر‎) was an Arab Muslim astronomer, mathematician, engineer and inventor who worked as muwaqqit (موقت, religious timekeeper) at the Umayyad Mosque in Damascus, Syria.

Ibn al-Shatir conducted extensive observations which led to some of his theoretical contributions, designed and constructed new instruments, and made advanced contributions to Islamic astronomy in the field of Planetary theory.