940-998

Persian mathematician and astronomer, also known as Abul Wefa, who developed the first wall quadrant, used for observing the movement of heavenly bodies. In a work written in 960, he discussed the oscillation or inequality in the motion of the Moon, a phenomenon also called variation. Contrary to the claims of some later historians, however, he did not discover this phenomenon. Abu al-Wafa, who spent much of his career working in a Baghdad observatory, is also known for his translations of ancient Greek texts and for his writings on applied mathematics.