A measurement of the ecliptic’s obliquity is later credited to Eratosthenes as a distinct astronomical heading
Dated 1 June 240: A measurement of the ecliptic’s obliquity is later credited to Eratosthenes as a distinct astronomical heading. In the causal graph this event strengthens Digital Learning Access, a driver that weakens Learning Poverty Rate (low- and middle-income countries) — an improving welfare path.
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Context
This is not the Syene well story.
Eratosthenes’s documented role is bounded by other offices and collaborators named in the sources below.
Conventional years are c.276–c.194 BCE. Almost no autograph survives. Cleomedes, Strabo, Nicomachus, and later encyclopedias are the public file. Classroom globe reconstructions are not his acts. Contribution is complex.
Why it matters
It is not a satellite series.
Who was responsible
Contribution type and responsibility level for each recorded actor — not sole-author shorthand.
Eratosthenes
PersonDirect responsibility
responsibility level 0.4 · verified
What changed
Fact → Driver → Indicator. Relationship strength orders the paths; it is not the observed indicator movement.
- FactA measurement of the ecliptic’s obliquity is later credited to Eratosthenes as a distinct astronomical heading
- strengthensDriverDigital Learning Access
- weakensIndicators (3)Learning Poverty Rate (low- and middle-income countries)
impact weight 0.5 · Effect from 1 June 240 · verified
It is not a satellite series.
Weakens · Relationship strength 0.2 (weight 0.5 × strength 0.4)
Observed
70% of 10-year-olds · 70 above the normal line (2022)
Worse than normalTwo readings: 57% of 10-year-olds (2019) and 70% of 10-year-olds (2022).
20192022 Above normal = worse
Strengthens · Relationship strength 0.17 (weight 0.5 × strength 0.35)
Observed
472 PISA score points · 28 below the normal line (2022)
Worse than normal7 readings, 2003–2022: fell from 499 PISA score points to 472 PISA score points.
Above normal = better
Weakens · Relationship strength 0.15 (weight 0.5 × strength 0.3)
Observed
11% of primary-school-age children · 11 above the normal line (2023)
Worse than normalAbove normal = worse
Evidence
The sources behind this fact and its verification state.
- 1.Britannica — EratosthenesEncyclopaedia Britannica · High credibility · verified
- 2.MacTutor — Eratosthenes of CyreneUniversity of St Andrews · High credibility · verified
What the sources establish
Britannica states that he measured the degree of obliquity of the ecliptic; MacTutor treats the same heading among the lost astronomical writings.
Britannica and MacTutor independently name an obliquity measurement under his heading.
Established: later scientific lives credit him with an obliquity figure. Not established: the observing log or that a modern textbook conversion is the autograph fraction.
Eratosthenes did not file a later UNESCO form, a later Loeb colophon, or a later museum label as a personal act. Split from the circumference row.
Causal path
How this event connects to drivers and indicators in the graph.
- ActorEratosthenes
- contributed toFactA measurement of the ecliptic’s obliquity is later credited to Eratosthenes as a distinct astronomical heading
- strengthensDriverDigital Learning Access
- weakensIndicatorLearning Poverty Rate (low- and middle-income countries)
Cite this page
Factrail. (2026). A measurement of the ecliptic’s obliquity is later credited to Eratosthenes as a distinct astronomical heading. Factrail. https://factrail.ai/facts/era-obliquity-ecliptic
https://factrail.ai/facts/era-obliquity-ecliptic
Accessed 16 October 2026.
By the Factrail desk · Method: how we source and score · Last reviewed
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