You know the story. Before 1492, everybody thought the Earth was flat, and if you sailed far enough west you’d drop right off the edge. Then brave Christopher Columbus ignored the Church and the scholars, sailed anyway, and proved them all wrong.

Almost none of that is true. And the smart-sounding correction most people learn next, “actually, everyone knew the Earth was round,” is only the first layer. There are two more myths underneath it.

Myth one: medieval people thought the Earth was flat

They didn’t. Educated people knew the Earth was round more than a thousand years before Columbus.

Around 240 BC, a Greek scholar named Eratosthenes didn’t just believe the Earth was round. He measured it. At noon on the summer solstice, the Sun stood straight overhead in the Egyptian city of Syene, and a vertical stick cast no shadow. At the same moment in Alexandria, farther north, a stick cast a shadow at about seven degrees, roughly one-fiftieth of a circle. So the distance between the two cities was about one-fiftieth of the way around the planet. Multiply by fifty and you have the whole Earth. Depending on how you convert his units, he came within a few percent of the real number.

That knowledge never went away. Medieval scholars wrote about a round Earth, and sailors watched ships disappear hull-first over the curve of the horizon. By Columbus’s time, the round Earth was old, settled science.

So the correction is true. But stopping there skips the only question that matters: if nobody believed it, where did the flat-Earth story come from?

Myth two: the story came down from the Middle Ages

It didn’t. It was popularized in the 1800s, and it was useful to the people who spread it.

In 1828, Washington Irving, the author of The Legend of Sleepy Hollow, published a hugely popular biography of Columbus. The real story of Columbus hunting for funding was fairly dull, so Irving added drama: a scene where Columbus faces down a council of ignorant churchmen who insist the world is flat. It’s a great scene. It’s also largely fiction.

It might have stayed a colorful exaggeration. But in the late 1800s, writers arguing that religion had always been at war with science needed an example of the Church crushing the truth, and the flat Earth was perfect. Two books did most of the work: John William Draper’s History of the Conflict Between Religion and Science (1874) and Andrew Dickson White’s A History of the Warfare of Science with Theology in Christendom (1896). By the twentieth century, the story was in classrooms everywhere. Historian Jeffrey Burton Russell, who traced how it spread, called it “the Flat Error.”

Myth three: Columbus was the visionary who was right

Here’s the twist inside the twist. There really was an argument about Columbus’s voyage. It just wasn’t about the shape of the Earth. It was about its size.

Columbus thought the Earth was about a quarter smaller than it really is. He leaned on a map associated with the Florentine scholar Toscanelli that shrank the ocean and, of course, showed no Americas. By his math, Asia was roughly 4,000 kilometers west of Europe. The real distance is more than 20,000.

The experts who reviewed his plan in Portugal and Spain told him so: his numbers were wrong, the ocean was enormous, and no ship of the time could carry enough food and water to cross it. They were right. Columbus survived because two continents nobody in Europe knew about happened to sit right where he would have run out of ocean.

So the brave visionary who was right when everyone else was wrong? He was wrong. The experts who doubted him? Correct. And the flat Earth they supposedly believed in? They never did.

The thing to take with you

When a story is this tidy (a lone genius, a world of fools, a clear villain), ask one question: who benefits from me believing this? The flat-Earth myth made the past look stupid and the present look brilliant, and it handed one side of a 19th-century argument a ready-made weapon. It wasn’t an accident. It was useful.

Feeling smarter than the past is a great feeling. Any time a story hands you that feeling for free, somebody is getting something out of it.

Questions people ask

Did people in the Middle Ages think the Earth was flat?

No. Educated Europeans accepted a round Earth throughout the Middle Ages. The Greeks had established it centuries earlier, and around 240 BC Eratosthenes measured the planet’s circumference to within a few percent.

Did Columbus prove the Earth was round?

No. Educated people already knew it was round. The real dispute was about the Earth’s size. Columbus thought it was about a quarter smaller than it is, and the experts who doubted his plan were right.

Who started the myth that medieval people believed in a flat Earth?

It was popularized in the 1800s, starting with a dramatic scene Washington Irving wrote into his 1828 biography of Columbus. Books by John William Draper (1874) and Andrew Dickson White (1896) then spread it as fact.

How did Eratosthenes measure the Earth?

He compared noon shadows in two Egyptian cities on the summer solstice. The shadow angle in Alexandria was about seven degrees, roughly one-fiftieth of a circle, so he multiplied the distance between the cities by fifty.

Why did experts reject Columbus’s plan?

Because his distance estimate was far too small. They argued, correctly, that the ocean between Europe and Asia was too wide for the ships of the time to cross without resupply.

Sources

• 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.
• Draper, J. W. (1874). History of the Conflict Between Religion and Science.
• White, A. D. (1896). A History of the Warfare of Science with Theology in Christendom.
• Vatican Observatory. Washington Irving’s Columbus and the Flat Earth.
• Encyclopedia.com. Eratosthenes of Cyrene.
• Wikipedia. Myth of the flat Earth.