Al-Urdi (full name: Muʾayyad (al‐Milla wa‐) al‐Dīn (Muʾayyad ibn
Barīk [Burayk]) al‐ʿUrḍī (al‐ʿĀmirī al‐Dimašqī) (مؤيد (الملة و) الدين (مؤيد ابن بريك) ألعرضي (العامري الدمشقي d.
1266) was a medieval Arab astronomer and geometer.
Born circa 1200,
presumably (from the nisba al‐ʿUrḍī) in the village of ʿUrḍ in
the Syrian desert between Palmyra and Resafa, he came
to Damascus at some point before 1239, where he worked as an engineer
and teacher of geometry, and built instruments for al-Malik
al-Mansur of Hims. In 1259 he moved to Maragha in
northeastern Iran, after being asked by Nasir al-Din al-Tusi to help
establish the Maragha observatory under the patronage
of Hulagu. Al-Urdi's most notable works are Risālat al-Raṣd,
a treatise on observational instruments, and Kitāb al-Hayʾa (كتاب الهيئة), a work on theoretical astronomy. His
influence can be seen on Bar Hebraeus and Qutb al-Din
al-Shirazi, in addition to being quoted by Ibn al-Shatir. Al-Urdi
contributed to the construction of the observatory outside of the city,
constructing special devices and water wheels in order to supply the
observatory, which was built on a hill, with drinking water. He also
constructed some of the instruments used in the observatory, in the year
1261/2. Al-Urdi's son, who also worked in the observatory, made a copy of his
father's Kitāb al‐Hayʾa and also constructed a celestial
globe in 1279.
Al-Urdi is a member of
the group of Islamic astronomers of the 13th and 14th centuries who were active
in the criticism of the astronomical model presented in Ptolemy's Almagest.
Saliba (1979) identified Bodleian ms. Marsh 621 as a copy of
Al-Urdi's Kitāb al-Hayʾa, based on which he argued that Al-Urdi's
contributions predated Al-Tusi. Otto E. Neugebauer in 1957
argued that the works of this group of astronomers, perhaps via Ibn
al-Shatir, must have been received in 15th-century Europe and ultimately
influenced the works of Copernicus. This concerns the "Urdi
lemma" in particular, an extension of Apollonius' theorem that
allowed an equant in an astronomic model to be replaced with an
equivalent epicycle that moved around a deferent centered at half the
distance to the equant point.
Apollonius's theorem
In geometry,
Apollonius's theorem is a theorem relating the length of a median of a triangle
to the lengths of its side. It states that "the sum of the squares of any
two sides of any triangle equals twice the square on half the third side,
together with twice the square on the median bisecting the third side".
Apollonius's theorem
In geometry,
Apollonius's theorem is a theorem relating the length of a median of a triangle
to the lengths of its side. It states that "the sum of the squares of any
two sides of any triangle equals twice the square on half the third side,
together with twice the square on the median bisecting the third side".
Sumber
Labels:
Mathematician
Thanks for reading Biografi Muʾayyad al-Dīn al-ʿUrḍī. Please share...!
