Urdi lemma

E311986

geometric theorem lemma

The Urdi lemma is a geometric theorem developed by the 13th-century astronomer Mu’ayyad al-Din al-Urdi that underpins non-Ptolemaic planetary models in medieval Islamic astronomy and later influenced Copernican astronomy.

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All labels observed (1)

Label	Occurrences
Urdi lemma canonical	2

Statements (31)

Predicate	Object
instanceOf	geometric theorem ⓘ lemma ⓘ
appliesTo	medieval Islamic astronomy ⓘ non-Ptolemaic planetary models ⓘ
describedIn	medieval Islamic astronomical treatises ⓘ
developer	Mu’ayyad al-Din al-Urdi ⓘ
field	astronomy ⓘ geometry ⓘ history of astronomy ⓘ
hasContext	geometrical transformations of circles ⓘ kinematic geometry ⓘ
hasDomain	mathematical astronomy ⓘ
hasEffect	preserves uniform circular motion in models ⓘ supports non-Ptolemaic kinematic schemes ⓘ
hasRole	foundation of non-Ptolemaic planetary kinematics ⓘ
historicalPeriod	medieval period ⓘ
inception	13th century ⓘ
influenced	Copernican astronomy ⓘ Nicolaus Copernicus’s planetary constructions ⓘ
languageOfOriginalWork	Arabic ⓘ
mainSubject	planetary models ⓘ
namedAfter	Mu’ayyad al-Din al-Urdi ⓘ
notableFor	impact on later European astronomy ⓘ role in the critique of Ptolemaic astronomy ⓘ
partOf	Maragha observatory ⓘ surface form: Maragha school of astronomy
relatedTo	Ibn al-Shatir planetary model ⓘ surface form: Maragha planetary models Ptolemaic system ⓘ surface form: Ptolemaic equant Tusi couple ⓘ
usedFor	constructing alternative planetary models ⓘ eliminating the equant ⓘ modifying Ptolemaic planetary models ⓘ

Referenced by (2)

Full triples — surface form annotated when it differs from this entity's canonical label.

Islamic astronomy → introducedConcept → Urdi lemma ⓘ

Tusi couple → relatedConcept → Urdi lemma ⓘ