Nur Ed-Din Al Betrugi

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For the crater, see Alpetragius (crater).

Nur Ed-Din Al Betrugi (also spelled Nur al-Din Ibn Ishaq Al-Bitruji and Abu Ishâk ibn al-Bitrogi; another spelling is al Bidrudschi) (known in the West by the Latinized name of Alpetragius) (died ca. 1204 AD) was an astronomer of the Middle Ages. Born in present-day Morocco, he settled in Seville, in Andalusia.

He became a disciple of Abubacer and was a contemporary of Averroës. Al Betrugi wrote the Kitab-al-Hay’ah, translated from the Arabic into Hebrew, and then into Latin (printed in Vienna in 1531).

He advanced a theory on planetary motion in which he wished to account for the phenomena peculiar to the wandering stars, by compounding rotations of homocentric spheres. This was a modification on Ptolemy's system of planetary motions. His efforts failed mainly because he followed Aristotle's notion of perfect or circular motion.

The Alpetragius crater on the Moon is named after him.

[edit] External links

• A. Zahoor, "Alpetragius"

This article incorporates text from the public-domain Catholic Encyclopedia.