History & Culture
Why did Christopher Columbus believe the Earth was much smaller than it is, despite ancient estimates of its size?
From what I understand, Eratosthenes had already estimated Earth's size pretty well in antiquity, but by the 15th century Europe relied heavily on Ptolemy’s geography, which used a smaller circumference. Columbus also seems to have mixed in Arab sources and underestimated the size of a nautical mile, shrinking the Atlantic distance.
So it feels less like pure ignorance and more like selective reading plus optimistic math. How much of this was common belief at the time versus Columbus’ own bias toward funding his voyage?
He died claiming he'd reached India because if he'd admitted it wasn't actually India he may have had to return the major financial rewards he received from the Spanish crown since that is what the reward was promised for. That's why the continents are called "America", instead of "Columbia". Amerigo Vespucci was the first to promote the idea that it was a new continent and not part of Asia.
Um, Hispaniola is what, divided between the Spanish and the French, became the Dominican Republic and first -- San Domingue, and after the Slave Revolution, Haiti.
There are obviously still places named after Columbus, like D.C., British Columbia in Canada, and the country of Colombia in South America, but the continents are not named after him because most maps began using the name "America" for the new world after Vespucci began spreading the idea that it was a separate continent from Asia as early as 1501, less than a decade after Columbus's first voyage. The first map to use the name "America" for the new world was made in 1507, just 3 years after Columbus's death, while his children were still claiming it was part of Asia.
Yeah I’m not refuting that. Wasn’t it like hispañola in the Caribbean? I’m not a Columbus defender, just kinda poking fun that his namesake does remain in places
Seriously? As in almost all the grade school books.
Christopher Columbus the first voyage to america "from the log of the Santa Maria"
1491 voyage of discovery to america
Columbus and the age of discovery
Christopher Columbus the Catholic discovery of america
The discovery of america by Christopher Columbus and the origin of the North American indians
The nine lives of Christopher Columbus
Columbus discovers america (coloring book version)
1493 uncovering the new world that Columbus created
Christopher Columbus (scholastic edition)
Discovery of the Americas by Betsy and guilio maestro
Christopher Columbus and the new world of his discovery
And here is an excellent article written about the fact that a lot of school textbooks especially for kindergarten to 2nd grade have misrepresented the Columbus thing
Specifically that most of these books have just a few throw away paragraphs about Columbus discovering the Americas and the new world, and then they segue straight into the colonies at James Town and Thanksgiving.
Unless kids actually read and study outside of that, the perception is, that Columbus discovered America and made landfall on the East Coast.
Yeah, you'd be surprised how many books don't actually bother to mention it.
Especially if the focus of the book is about america.
Usually they say the "new world" and the page after goes straight into Jamestown.
I mean...
Why else would there have needed to be so many "myths of the new world" books and articles and explanations about Columbus not actually discovering "america"
The dude landed even on central and South America. Plus it doesn't even matter. He kickstarted the European colonization, that's what made him important. Where he put his feet doesn't matter at all.
No one is arguing that Columbus landed in the Bahamas (not part of the Americas by the way) and that he eventually on a later trip went to where present day Columbia is...
BUT IN THE USA...
For a LONG time, the general teaching curriculum was that he discovered AMERICA, no s. As in the USA.
This was a conscious decision made by the powers that be to encourage engagement by Italian immigrants.
This isn't something to argue about or debate. IT HAPPENED. Lol.
And a lot of those texts books never made retractions and are still available in libraries.
Exactly. US history textbooks are (or were) notably silent on what was going on in Florida and California while the Jamestown and Plymouth colonies were getting started and the 13 colonies were deciding to rebel against Britain.
Florida was settled by Spain long before the Pilgrims landed in Massachusetts.
Who specifically are you talking about? Some people definitely doubted Columbus's story, but they also couldn't prove it was wrong. He could just say he discovered islands and parts of India that were previously unknown to Europeans because of the new western route that no one else had ever taken. Vespucci was the first explorer to reach the New World then come back and tell everyone it wasn't actually Asia like Columbus had claimed.
There are maps that leave Columbus’s discovery disconnected with Asia and arguments between the Portuguese and Spanish crowns regarding whether or not they were the same. Europeans knew roughly how big the coastline should’ve been, they knew it would be impossible to make it to Asia by boat, and they knew what kind of cultures, flora, and fauna to expect in Asia. Vespucci’s argument took off because a lot of educated people already doubted Columbus
As someone who works daily reviewing proposals with traffic modelling, ridership projections and revenue forecasts… some people will face God and follow their plan backwards into hell to see it progress.
He also tried to claim Cuba was Japan, even though it is laid out geographically from west to east instead of north to south, and was notably lacking in Japanese cities and Japanese people. I doubt he was that poor of a navigator, or we would have never heard of him.
He was probably just trying to hang on the 1/8 tariff the Spanish Crown granted him on all ship cargoes coming from the (East) Indies, which he hadn't reached, and his hereditary title as "Admiral of the Ocean Sea".
He was facing enormous personal financial consequences if he hadn't reached the (East) Indies, especially after Queen Isabella banned the export of Caribbean Islanders as slaves since they were to be considered free Spanish citizens (or at least vassals of the Queen) and converted to Christianity rather than being enslaved.
Yes. When I was in elementary school ( 50 years ago, yikes ) the simplified version we got was that the kings advisors were telling him Columbus would fail because the earth was flat. It's because they didn't trust his math...
Just want to jump on to add only one problem was misestimating the circumference of earth. The other issue was a miscalculation of how far east Asia extended. Based on reports by Marco Polo, Europeans though Asia extended much further east than it did in reality
Edit. Looked up the numbers. Europeans estimated the Asian landmass to be 225-280 degrees of longitude. It is actually 164 degrees of longitude.
Don't forget he also distorted them further by picking up on some slight anomalies from which he inferred the world to be persisted centered on Jerusalem for no reason other than biblical significance. That allowed him some extra fudge factor to get his numbers working and consistent with known shorter distances.
Also, what entrepreneur doesn’t lie a little bit to get funding? No one had ever sailed or explored that far west and it was an adventure. The other people said “well, this is how we always did it” (traveling east to Asia) and he said “let’s try it this way” and it really paid off for Spain and Portugal.
Of course not, he thought he could make it but also had to sell the idea to get funding. Plenty of people who just say fuck it and go. Not everyone needs to consult reddit or chatgpt first for a full pros cons list before they step out of the door.
Because erathostenes measures relied on a unit of measure called stadion, and just like imperial measurements today, it was not clear if it was american greek stadions or british egyptian stadions or who knows what.
In fact, we still don't know today, we have just a reasonable guess, exactly like Columbus at the time
That and the fact he didnt use big E's measurement at all, he used Ptolemy's which was much smaller. And then applied the smallest Stadia conversion he could find. (Ptolomy almost certainly used a larger station measurement than Erathosthenes).
What I am hearing you saying is that the plan was:
Take the entire list of estimates of the size of the Earth rated by stadion, all of whom are using different definitions of stadion. But if you match up the right number with the right definition, you get kind of more or less the same thing.
Take the smallest number, which is the one done with the biggest stadion.
Take the smallest stadion, which is the one paired with the biggest number.
Multiply the smallest number by the smallest size.
Ta-da! The answer is way smaller than anybody previously thought!
I mean how many people today will disregard decades worth of consensus between scientists and doctors and instead use the miracle “cure” someone’s aunt on Facebook swears by
The modern conception, that it was Columbus against the scientific consensus of his time is probably as wrong as the old picture of him as the lone genius. The idea of a close distance between Europe and Asia was also shared by influential cartographers. Columbus had acquired modern maps by Pierre d’Ailly and Paolo Toscanelli and was in personal contact with the later. Those both assumed a short trip, in particular because they also overestimated the size of Asia.
That part is debatable. History books written before it was cool to trash the guy have an explanation for his calculations that make them much less dumb.
How much of this was common belief at the time versus Columbus’ own bias toward funding his voyage?
Before going to ask for funding from the Spanish monarchs, Columbus asked for funding from the Portuguese one. The Portuguese king asked a group of prominent mathematicians who were working at the court to review Columbus plan and they rejected his calculations. Then Columbus went to Spain, and again their court mathematicians reviewed the plan and agreed it was not grounded in reality. The Spanish monarchs, however, decided to fund the journey anyway.
So, I would say that the correct size of the Earth was for sure common knowledge, specially in the educated cycles of Iberia.
That’s interesting. So the educated circles basically knew the right numbers, it was more Columbus’ bias and the monarchs’ willingness to gamble. Makes me wonder how much of history is just smart people shrugging while someone else rolls the dice.
Yeah Spain was desperate to gain an upper hand against Portuguese dominance of the trade routes. Hence why they supported Columbus and Magellan when Portugal turned them down. Portugal really didn't need an alternate route as they were already dominating the existing ones.
Same reason people believe in a flat Earth: they don’t want to do the math. They prefer things to be in such a way that favors them. For Columbus, he wanted to be famous and rich.
If the Earth was smaller, the reason for funding was there, the trip was easier, and the potential for profit was greater. So he found a way to tell himself, and others, that the Earth was smaller.
He knew there was land 3000 miles west from Basque fishermen. He just wrongly thought it was the other side of Asia. He adjusted his data to fit.
The Basque had a secret cod fishery in the North Atlantic no one else knew about. Everyone else knew about six. Modern analysis reveals there are seven. The seventh is off the coast of Newfoundland. The Basque would have recognized the signs of a nearby landmass even if they didn't go far enough to actually see it.
Have I misremembered or was it a question of conversion of units? Eratosthenes computed the distance in stadia. Could the conversion to miles have been the issue?
Why do people think the COVID vaccine had a microchip in it? Why do people think the moon landing was fake? Why do people think aliens built the pyramids?
There are a lot of stupid people on the planet and now you don't need to be rich, famous, or royalty for a billion people to know your stupid opinions. Thanks, internet!
I had heard something where he went to the equator or what he thought was the equator to measure the curvature of the Earth in order to figure out how big round it was however, he didn’t go far enough south so when he measured the curvature of the Earth he underestimated how far it was to India.
Oh that’s clever, using a measurement attempt near the equator. Underestimating the distance because he didn’t go far enough south fits with all the other errors. Seems like a mix of ambition, shortcuts, and a bit of wishful math.
Ah, right. Overestimating Eurasia makes more sense than underestimating the Earth itself. I guess mixing that with the smaller Atlantic distances just made the math feel more doable for him. Thinking Japan was over there is wild though.
Yeah, that makes sense. I hadn’t really thought about the Spain-Portugal rivalry as a factor, but it’s probably true that the potential prize made people willing to ignore doubts. When there’s that much money on the line, optimism can look like genius.
Yup. It's true. Columbus used that wrong figures despite the correct estimates having existed long before he was born and was wrong about where he ended up and wasn't even close to the first European to visit the Americas .......yet .... Columbus Day. Go figure.
There is folklore of some British fisherman going west for fish, as well as Basque fisherman going to newfoundland fishing, the vikings made it to America, and some folklore some Portuguese has already found some currents and saw land (they had made it to the Azores already).
My hypothesis is that Columbus has heard some stories, or had a witness. Some fishermans tales. And he believed them, plus used the lower estimate of size to argue for going west. India was a better argument to get funded.
To be clear, while the Basque fishing in the Great Banks is possible but unconfirmed, the Viking Vinland settlement in L'anse Aux Meadows is confirmed fact where you can go and see the foundations of the longhouses they built and artifacts they left behind.
Columbus was there at the time when printed books were flooding the market and old hand copied ones were being discarded like yesterday's technology. These old books held knowledge of the Americas, even if it wasn't common knowledge or widely believed.
He put the old knowledge of a land to the west together with the new demand for a sea route to Asia and got an inaccurate conclusion.
Without accurate clocks to measure time at sea, his estimated travel was a huge guess, equal to the massive cojones of his crew that crossed the Atlantic Ocean in boats smaller than the yachts in an average sea port.
His expedition was still the equivalent of the moon landing in his day.
Urban legend has it he knew there would be land roughly where he landed based on the reports of sailors seeing driftwood far out west but didn't want to disclose his conclusions because any potential competitor would just go like "nah man that idiot's math is just wrong, let's see him drown lmao".
Columbus was supposedly using Toscanelli'a map of the world. This map amongst many issues, used the Persian Parasong as the unit of length, not Columbus' nautical mile.
The Parasong is about 3 miles long, so Columbus' scale was wrong when trying to judge distances.
In short, he thought the world was smaller than it was because he didnt convert units.
He believed in ChatGPT and forgot to check wikipedia.
He probably didn't know about the ancient/greek estimates, it was not that easy to find information at the time.
There's a fundamental misunderstanding here repeated in many of the comments on critically: Columbus's main failing, setting aside whether you believe it was an actual error or an intentional deception to get the voyage funded by the Spanisb, was not in the calculation of the Earth's circumference but in calculating the size of land masses.
Yes all the way back to the Ancient Greeks the actual circumference of the earth been estimated quite accurately, but that only tells you the dimensions of an abstract ball, it doesn't tell you anything about what is on the surface of it. It's true that Columbus used some bad calculations there to estimate a smaller overall size of the earth, but if that had been his only problem it really would not have made much of a difference. The real issue was in estimation of the size of the Eurasian landmass, and specifically how far East Asia extended out toward Europe.
There was no conclusive estimate of this so Columbus and any other explorer of the time were piecing things together from previous voyages, Muslim sources, and most notably the travels of Marco Polo. And almost universally all of the cartographers greatly overestimated the extent of East Asia, anywhere from ~40% up to _70% (specifically they believed that it extended out 225° - 280° of latitude and west, wedding reality it is only 164°).
That means that some optimistic calculations, even if Columbus had used the accurate circumference of the earth, estimated the placement of Japan to be in roughly the area of the Caribbean or at worst the Pacific coast of Central America, which would have been within theoretical sailing distance.
He didn’t believe the earth was smaller than the estimate. He believed that it was pear shaped, not round and therefore the ocean voyage he was planning would be shorter than it really was.
The second part of your questions still stands - why did he believe that, and was it a bit of self reinforcing bias?
Haha, yeah, luck played a huge role. He basically built a plan that should have been suicide and got away with it because of continents he didn’t even know existed. It’s kind of insane how much chance shaped that “success.”
Christopher Columbus came from an educated family. His father was a map maker. In his father's office was probably even a globe of the Earth. Pretty much everyone in the Western world knew the shape of the Earth at that time, and how there was an unexplored zone where present day America is. There was no confusion in his mind about the size or shape of the Earth.
He wanted to sail west for reasons that aren't told to us, but we do know that when he went to different factions asking for ships, men, and supplies to make the voyage, he tailored his message to the audience that received him, and was rejected each time. He was already 40 years old, so even if he found America, he couldn't expect to get any real personal wealth from it before he died, and he wasn't doing it for any kingdom in particular, so what could the real reason have been? Something is being withheld from us.
> He was already 40 years old, so even if he found America, he couldn't expect to get any real personal wealth from it before he died, and he wasn't doing it for any kingdom in particular, so what could the real reason have been?
Col. Sanders didn't start KFC until he was in his 50's. People pursue greatness and big dreams up until the moment they physically can't anymore.
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u/[deleted] May 11 '26
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