Islamic · 13th century CE (al-ʿUrḍī d. 1266)

Treatise on planetary retrograde motion

Attributed to Muʾayyad al-Dīn al-ʿUrḍī

A short treatise devoted to retrogression, attributed to al-ʿUrḍī of the Maragha observatory. It notes that retrograde loops vary in shape and size across the sky, that a concentric epicycle-and-deferent model gives uniform loops that do not match observation, so an eccentric model is needed, and, instead of testing each planet's parameters separately as Almagest XII does, offers a general rule for the phenomenon based on Apollonius' theorem.

Author: Muʾayyad al-Dīn al-ʿUrḍī (attributed)
Date: 13th century CE (al-ʿUrḍī d. 1266)
Original language: Arabic
Kind: Theory / model
Planets: Mercury, Venus, Mars, Jupiter, Saturn

On the shelf · Asia, Islam and medieval Europe · 11−1800 → 2026

−1800−1500−1000−5001500100015002026

Span · 13th century CE (al-ʿUrḍī d. 1266)Same shelfThis source’s span

Editions

One edition.

Year	Edition	©
2020	Zamani, Maryam. 'Planetary Retrograde Motion in a Treatise Attributed to Muʾayyad al-Dīn al-ʿUrḍī.' Tārīkh-i ʿIlm (Journal for the History of Science, Univ. of Tehran) 18.2 (2020), issue 29: 41–82. DOI 10.22059/jihs.2021.315968.371608.	?

? unclear

Read it

One digitised copy.

Zamani 2020, a modern article about the treatise (not the treatise itself)Journal for the History of Science, University of TehranCC BYOpen ↗

References

Zamani (2020), Tārīkh-i ʿIlm / Journal for the History of Science, University of Tehran

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