Ancient people believed the Earth was flat
Scientific Reality
Educated people from ancient Greece onward knew Earth was spherical — Eratosthenes measured its circumference around 240 BC.
Historical & Cultural Context
The belief was handed down through school textbooks, national folklore, and popular retellings. As a question of antiquity, "Ancient people believed the Earth was flat" slotted neatly into what people already expected to be true, which is exactly why it went unquestioned for so long.
Each generation repeated it with more confidence than evidence, and vivid stories outcompeted dry accuracy. It was not until 1991 that the record was set straight — educated people from ancient Greece onward knew Earth was spherical — Eratosthenes measured its circumference around 240 BC. The correction came from Inventing the Flat Earth (Russell, 1991), yet the original myth still lingers in everyday conversation.
A Different Lens
What endures is rarely what happened — it is what makes the best story. This myth reveals how collective memory edits the past for meaning, not precision. It persists by living in the comfortable middle ground between plausible-sounding and actually verified. Strip away the folklore and the sharper truth comes into focus — start with a single fact: eratosthenes measured Earth’s circumference c. 240 BC. Seen this way, the myth is less a mistake to mock than a case study in how belief outruns evidence.
Deep Dive
Aristotle offered empirical proofs of sphericity; Eratosthenes calculated circumference with startling accuracy; medieval universities taught the sphere as standard. Historian Jeffrey Burton Russell traced the "everyone thought it was flat" story to 19th-century writers dramatizing Columbus.
- Eratosthenes measured Earth’s circumference c. 240 BC
- Aristotle cited ship hulls and eclipse shadows as proofs
- Medieval texts like Sacrobosco’s "De Sphaera" taught sphericity
- The flat-medieval myth was popularized by Washington Irving’s fiction
Visualization
Eratosthenes’ Shadow Experiment
Using well shadows at Syene and Alexandria, Eratosthenes computed Earth’s circumference within a few percent — 1,700 years before Columbus sailed.
Verified Sources & Peer-Reviewed References
Inventing the Flat Earth
Praeger·1991Eratosthenes’ Measurement of the Earth
Isis·1982De Sphaera Mundi
Johannes de Sacrobosco·1230A History of the Warfare of Science with Theology
Appleton·1896
All sources are peer-reviewed or from accredited space agencies. Dark Myths does not fabricate or misrepresent scientific findings.