On the Measurement of the Earth
E728495
"On the Measurement of the Earth" is an ancient treatise in which Eratosthenes used geometric reasoning and observations of the Sun to calculate the Earth's circumference with remarkable accuracy.
Statements (42)
| Predicate | Object |
|---|---|
| instanceOf |
ancient scientific treatise
ⓘ
work on astronomy ⓘ work on geodesy ⓘ |
| angleApproximation | about one-fiftieth of a full circle ⓘ |
| angleMeasured | difference in solar elevation between Syene and Alexandria ⓘ |
| assumption |
Sun is very far from Earth
ⓘ
Syene and Alexandria lie approximately on the same meridian ⓘ distance between Syene and Alexandria is known ⓘ |
| author | Eratosthenes NERFINISHED ⓘ |
| basedOnObservation |
solar altitude at Alexandria
ⓘ
solar altitude at Syene ⓘ |
| calculationType | circumference from central angle and arc length ⓘ |
| distanceSegment | Syene–Alexandria arc NERFINISHED ⓘ |
| field |
astronomy
ⓘ
geodesy ⓘ geometry ⓘ |
| genre | scientific prose ⓘ |
| historicalPeriod | Hellenistic period NERFINISHED ⓘ |
| influenced |
history of geography
ⓘ
later estimates of Earth's size ⓘ later geodesy ⓘ |
| influencedBy | earlier Greek geometry ⓘ |
| keyConcept |
angle of the Sun at local noon
ⓘ
parallel rays of sunlight ⓘ proportionality between arc length and central angle ⓘ spherical Earth ⓘ |
| knownFrom |
Cleomedes' writings
ⓘ
accounts by later authors ⓘ |
| language | Ancient Greek ⓘ |
| mainSubject |
Earth
NERFINISHED
ⓘ
Earth's circumference ⓘ |
| measurementUnit | stadion ⓘ |
| notableFor |
early quantitative measurement of a planetary body
ⓘ
remarkable accuracy of Earth's circumference estimate ⓘ |
| placeOfOrigin | Alexandria NERFINISHED ⓘ |
| preservationStatus | survives only in later reports ⓘ |
| relatedWork | Geographika NERFINISHED ⓘ |
| result | approximate value for Earth's circumference ⓘ |
| scientificSignificance |
demonstration of Earth's large but finite size
ⓘ
early example of empirical Earth measurement ⓘ |
| usesMethod |
geometric reasoning
ⓘ
observation of the Sun ⓘ |
Referenced by (1)
Full triples — surface form annotated when it differs from this entity's canonical label.