# Did Medieval People Think the Earth Was Flat? History · 6 min read · updated 2026-10-30 > Educated Europeans knew the Earth was round for 2,000 years before Columbus. What his critics really argued, and how a 19th-century story invented the myth. ## The short answer No. Educated Europeans had known the Earth was round since ancient Greece, and medieval scholars, textbooks and kings’ regalia all assumed a sphere. Columbus’s critics argued he’d underestimated its size, and they were right. The idea that medieval people believed in a flat Earth was largely popularised in the 19th century, notably by Washington Irving’s 1828 biography of Columbus. In the classic version of the story, Christopher Columbus stood before a council of fearful churchmen who were certain the Earth was flat and that his ships would sail off the edge. Brave, modern-minded Columbus defied them, set off west in 1492, and proved them wrong. It’s a stirring story. It’s also a myth, and a surprisingly young one. Educated Europeans had known the Earth was a sphere for well over a thousand years before Columbus set sail, and his critics weren’t worried about an edge at all. They were worried, correctly, about arithmetic. Step through the timeline at the top to see when each piece of the real story happened. ## The Greeks worked it out first By the 5th century BC, followers of Pythagoras were teaching that the Earth was a sphere, partly for philosophical reasons: a sphere was the perfect shape. By the 4th century, Greek thinkers had better reasons. Aristotle, writing around 350 BC, pointed to the curved shadow the Earth casts on the Moon during a lunar eclipse. The shadow is always round, whatever the angle, and only a sphere casts a round shadow from every direction. He also noted that travellers going south see new stars rising above the southern horizon, which only makes sense if the ground beneath them curves. ## A measurement, not just an argument Around 240 BC, Eratosthenes, the chief librarian at Alexandria, went further: he measured the Earth. He’d heard that at noon on midsummer’s day, the Sun shone straight down a well at Syene, in southern Egypt, so that it cast no shadow. At the same moment in Alexandria, to the north, a vertical stick cast a short shadow, at an angle of about a fiftieth of a full circle. If the Sun’s rays arrive parallel, that angle is how far apart the two cities are around the curve of the Earth. Multiply the distance between them by fifty and you have the whole circumference. *(An interactive illustration belongs here. Try it on the page: https://cognosc.com/blog/flat-earth-myth)* His answer was about 250,000 stadia. Historians argue about exactly how long his stadion was, but on most readings the answer comes within a few per cent to perhaps fifteen per cent of the modern 40,075 kilometres. Two thousand two hundred years ago, with a stick, a shadow and some careful thinking, someone sized the planet. ## Medieval scholars kept the round Earth This knowledge wasn’t lost in the Middle Ages, though the myth says it was. - The English monk **Bede**, writing in the early 700s, described the Earth as a globe, and explained the uneven lengths of daylight in different places by its curve. - **Johannes de Sacrobosco**’s *On the Sphere*, written around 1230, was a standard astronomy textbook in European universities for four centuries. Its title says it all. - **Dante**’s *Divine Comedy*, finished around 1320, takes its travellers down through the Earth and out the other side, where they see unfamiliar stars in the southern sky. It assumes a sphere so completely that it doesn’t bother to argue for one. - Kings and emperors were painted holding a **globus cruciger**, an orb topped with a cross, a symbol of rule over a round world. A few early Christian writers did argue for a flat Earth. Lactantius, around 300 AD, mocked the idea of people living upside down on the other side, and a 6th-century traveller called Cosmas wrote a book describing the world as a flat tabernacle. But they were exceptions, and scholars of the time regarded them as eccentric. They’re remembered now mostly because later writers dug them up as evidence for something that wasn’t true. ## So what did Columbus’s critics argue? They argued about **size**, and they were right. In the late 1480s, a commission of scholars appointed by the Spanish crown examined Columbus’s plan to reach Asia by sailing west. They knew the Earth was round. Working from estimates descended from Eratosthenes, they knew roughly how big it was, and so they knew that sailing west from Spain to Asia meant crossing an enormous ocean, far more than any ship of the time could survive without landfall. *(An interactive illustration belongs here. Try it on the page: https://cognosc.com/blog/flat-earth-myth)* Columbus had squeezed the numbers. He took a small estimate of the Earth’s size, partly by reading an Arab geographer’s miles as shorter Roman miles. He also took a very generous estimate of how far east Asia stretched, which shrank the gap still further. By his sums, Japan lay only a few thousand kilometres west of the Canary Islands, roughly where America actually is. The true distance is about four times that. He wasn’t a visionary proving the experts wrong. He was a determined man with bad numbers, who survived only because an entire continent nobody in Europe knew about happened to be in the way. To the end of his life, he insisted he’d reached Asia. ## Where the myth came from If medieval people knew the Earth was round, where did the flat-Earth story come from? Mostly from the 19th century. - **Washington Irving**’s hugely popular 1828 biography of Columbus dramatised a scene of Columbus facing churchmen who believed the Earth was flat. Irving was a skilled storyteller, best known for *Rip Van Winkle*, and much of the scene was invented. - Later in the century, writers including **John William Draper**, in 1874, and **Andrew Dickson White**, in 1896, wrote books casting science and religion as ancient enemies. A Middle Ages that believed in a flat Earth, until brave explorers proved otherwise, fitted their story perfectly, and they repeated the claim as fact. - From there it entered school textbooks, which copied one another for generations. The historian **Jeffrey Burton Russell** traced this in his 1991 book *Inventing the Flat Earth*. The myth, he argued, says more about the 19th century than about the Middle Ages: it let a confident, industrial age see itself as the one that had finally escaped superstition. ## How you can see it for yourself You don’t need a satellite to see the Earth’s curve. The clues the Greeks used still work. - **Ships go hull first.** Watch a ship sail away on a calm day with binoculars, and the hull disappears below the horizon before the mast. - **The Moon’s eclipse shadow is round.** At every lunar eclipse, at every angle. - **The Pole Star sinks as you go south.** It stands high over the Arctic, at about 52 degrees above the horizon in London, and drops below the horizon as you cross the equator. - **Time zones exist.** When it’s noon in London, it’s night in Sydney. A flat Earth lit by a single Sun can’t do that. ## What about modern flat-earthers? Here’s an irony. The belief the myth pins on the Middle Ages is far more visible today than it was then. The modern flat-Earth movement grew from a 19th-century English writer, Samuel Rowbotham, who argued for a flat Earth from careful-looking “experiments” on a long, straight canal. A Flat Earth Society was founded in 1956, and the idea found a new audience online in the 2010s. It’s still a tiny minority view. But it shows that a flat Earth isn’t a primitive belief that science swept away. It’s a modern one, held in an age of satellites, which says something about how beliefs spread: through communities and stories more than through evidence. ## Why the myth stuck It’s a good story: one brave man against a superstitious crowd. It flatters us, the moderns who know better. And it’s been told so many times that it feels like something everybody has always known. That’s worth noticing, because it’s how most history myths survive. They’re usually simple, vivid and slightly flattering to the person repeating them. The real history, of Greek geometers, monastic astronomers and a sailor with bad arithmetic, is less tidy and more interesting. The free [history myths test](/test/history) asks about this and nineteen other things people get wrong about the past. For more like it, see [seven history myths, debunked](/blog/history-myths). ## What to remember - Greek thinkers had shown the Earth was round by the 4th century BC, and Eratosthenes measured it around 240 BC. - Medieval scholars kept that knowledge: Bede, university textbooks and the orb in a king’s hand all assumed a sphere. - Columbus’s critics knew the Earth was round. They argued it was too big to sail around to Asia, and they were right. - The flat-Earth story was popularised in the 1800s, by Washington Irving and by writers casting science and religion as enemies. - A myth that flatters the present at the expense of the past is especially easy to believe. ## Questions people ask ### Did people in the Middle Ages believe the Earth was flat? Educated people didn’t. Medieval scholars such as Bede and the authors of university textbooks described a spherical Earth, and the idea was standard from ancient Greece onwards. A few early writers argued for a flat Earth, but they were exceptions. What ordinary farmers believed is less recorded. ### Who first proved the Earth is round? Greek philosophers in the 5th and 4th centuries BC. Aristotle gave evidence around 350 BC, including the round shadow Earth casts on the Moon during an eclipse. Around 240 BC, Eratosthenes estimated its size using the angles of shadows in two Egyptian cities. ### What did Columbus’s critics argue? That the ocean between Europe and Asia was far too wide for his ships to cross. They were working from good estimates of the Earth’s size. Columbus had shrunk the planet and stretched Asia, and he reached land only because the Americas were in the way. ### Where did the flat-Earth myth come from? Largely from the 19th century. Washington Irving’s 1828 biography of Columbus invented a scene of churchmen insisting on a flat Earth, and later writers such as John William Draper and Andrew Dickson White spread the idea in histories about a war between science and religion. ### How can you tell the Earth is round without a satellite? Ships disappear hull first over the horizon. The Earth’s shadow on the Moon during an eclipse is always round. The Pole Star sits lower in the sky the further south you travel. And the Sun stands at different heights at the same moment in different cities. ## Sources and further reading - Russell, J. B. (1991). Inventing the Flat Earth: Columbus and Modern Historians. Praeger. - Irving, W. (1828). A History of the Life and Voyages of Christopher Columbus. London: John Murray. - Numbers, R. L. (ed.) (2009). Galileo Goes to Jail and Other Myths about Science and Religion. Harvard University Press. - Aristotle. On the Heavens (De Caelo), Book II. - Sacrobosco, J. de (c. 1230). De sphaera mundi (On the Sphere). - Morison, S. E. (1942). Admiral of the Ocean Sea: A Life of Christopher Columbus. Little, Brown. --- Canonical page: https://cognosc.com/blog/flat-earth-myth From Cognosc (https://cognosc.com): free tests, articles and an AI tutor that has you reason things through.