Knowra Ibn Yunus Ibn Yunus Abū al-Ḥasan ʿAlī ibn ʿAbd al-Raḥmān ibn Aḥmad ibn Yūnus al-Ṣadafī was an Egyptian Muslim astronomer and mathematician active around the turn of the eleventh century. His precise observations and astronomical tables became influential in Islamic astronomy.
Astronomical table : A structured set of numerical values used to calculate positions or motions of celestial bodies. Ibn Yunus’s tables organized computed positions and astronomical parameters for practical calculation.
Zij al-Kabir al-Hakimi : Ibn Yunus’s major astronomical handbook, containing observations, tables, and computational procedures. This is the principal work through which his observational and mathematical results were transmitted.
Fatimid Caliphate : A Shiʿi Muslim caliphate that ruled parts of North Africa and the Middle East from 909 to 1171. Ibn Yunus worked in Fatimid Egypt, where court support helped sustain astronomical scholarship.
Ibn al-Haytham : An Arab mathematician and natural philosopher known for major contributions to optics and scientific inquiry. Ibn al-Haytham was among the scholars connected to the intellectual world of Fatimid Egypt.
Astrolabe : An instrument that models the celestial sphere and supports astronomical measurement and calculation. Astrolabes formed part of the observational and computational tradition surrounding his work.
Solar eclipse : An event in which the Moon passes between Earth and the Sun, obscuring some or all of the Sun. Eclipse observations provided demanding tests of the timing and accuracy of astronomical calculations.
Cairo : The capital city of Egypt, founded by the Fatimids in 969. Cairo was the setting for his career and the observations associated with his astronomical work.
Al-Biruni : A Persian polymath who wrote extensively on astronomy, mathematics, geography, and comparative religion. His references to earlier astronomical results help situate Ibn Yunus within a broader scholarly network.
Astronomical observation : The systematic measurement of celestial positions, motions, or events. His tables drew authority from a large program of careful observations.
Lunar eclipse : An event in which Earth’s shadow falls on the Moon. Records of lunar eclipses helped establish and compare celestial positions across time.
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