Al-Ashraf Umar II
Al-Ashraf's diagram of the compass and Qibla, copied in Yemen, 1293.
|Died||22 November 1296|
al‐Malik al‐Ashraf (Mumahhid al‐Dīn) ʿUmar ibn Yūsuf ibn ʿUmar ibn ʿAlī ibn Rasūl (born c. 1242, died 22 November 1296 in Yemen) was the third Rasulid sultan and a polymath. He is known for writing the first description of the use of a magnetic compass for determining the qibla. Also, his works on astronomy contain important information on earlier sources.
In a treatise about astrolabes and sundials, al-Ashraf includes several paragraphs on the construction of a compass bowl (ṭāsa). He then uses the compass to determine the north point, the meridian (khaṭṭ niṣf al-nahār), and the Qibla towards Mecca. This is the first mention of a compass in a medieval Islamic scientific text and its earliest known use as a Qibla indicator, although al-Ashraf did not claim to be the first to use it for this purpose.
- Schmidl, Petra G. (1996–97). "Two Early Arabic Sources On The Magnetic Compass". Journal of Arabic and Islamic Studies. 1: 81–132. http://www.uib.no/jais/v001ht/01-081-132schmidl1.htm#_ftn4 Archived 2014-09-02 at the Wayback Machine
- Schmidl 2007.
- Schmidl, Petra G. (2007). "Ashraf: al‐Malik al‐Ashraf (Mumahhid al‐Dīn) ʿUmar ibn Yūsuf ibn ʿUmar ibn ʿAlī ibn Rasūl". In Thomas Hockey; et al. (eds.). The Biographical Encyclopedia of Astronomers. New York: Springer. pp. 66–7. ISBN 9780387310220. (PDF version)
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