In 1492, Columbus sailed the ocean blue…

Alright, so I know Columbus day was last week, but I thought I’d throw this out there anyway, as it’s been a perennial mystery for me.

One of the myths we tell schoolchildren is that “Columbus discovered the Earth was round”. Now, anyone with half a brain today knows that anyone with half a brain back then knew the Earth was round already. Columbus knew it, and so did the Spanish royalty he pitched his idea to.

The amazing thing though has nothing to do with the Earth being round vs flat, but rather, just how big the Earth is. You see, as early as the ancient Greeks, people knew the Earth was round. They even had a pretty good idea of just how big it was – Eratosthenes nailed it to within about 2% in 240 BC and Ptolemy was another one who got pretty close a little later in history. There was a steady stream of scholars after that who estimated the modern number pretty closely using various methods.

So, here’s the problem: Europeans didn’t know that the Americas were there. So using the most accurate numbers available to them, that put 12,000 miles of ocean between the west coast of Europe and the east coast of Asia. Basically, an impossibly long voyage in 1492.

Columbus however, he got the idea in his head that the distance wasn’t 12,000 miles, but rather 3,000 miles (coincidentally, roughly the distance to the east coast of America). Wikipedia explains it:

Following Washington Irving’s myth-filled 1828 biography of Columbus, it became common supposed knowledge that Columbus had difficulty obtaining support for his plan because Europeans believed that the earth was flat. In fact, few people at the time of Columbus’s voyage, and virtually no sailors or navigators, believed this. Most agreed that the earth was a sphere. Indeed, knowledge of the Earth’s spherical nature was not limited to scientists: for instance, Dante’s Divine Comedy is based on a spherical Earth. Columbus put forth arguments that were based on the circumference of the sphere. Most scholars accepted Ptolemy’s claim that the terrestrial landmass (for Europeans of the time, comprising Eurasia and Africa) occupied 180 degrees of the terrestrial sphere, leaving 180 degrees of water.

Columbus, however, believed the calculations of Marinus of Tyre that the landmass occupied 225 degrees, leaving only 135 degrees of water. Moreover, Columbus believed that 1 degree represented a shorter distance on the earth’s surface than was commonly held. Finally, he read maps as if the distances were calculated in Italian miles (1,238 meters). Accepting the length of a degree to be 56? miles, from the writings of Al-Farghani, he therefore calculated the circumference of the Earth as 25,255 kilometers at most, and the distance from the Canary Islands to Japan as 3,000 Italian miles (3,700 km). Columbus did not realize that Al-Farghani used the much longer Arabic mile of about 1,830 meters.

The problem facing Columbus was that experts did not accept his estimate of the distance to the Indies. The true circumference of the Earth is about 40,000 kilometers, and the distance from the Canary Islands to Japan is 19,600 kilometers. No ship in the 15th century could carry enough food to sail from the Canary Islands to Japan. Most European sailors and navigators concluded, correctly, that sailors undertaking a westward voyage from Europe to Asia non-stop would die of starvation or thirst long before reaching their destination. Spain however, only recently unified through the marriage of Ferdinand and Isabella, was desperate for a competitive edge over other European countries in trade with the East Indies. Columbus promised them that edge.

So Columbus thought the distance was 3,000 miles. The rest of the world thought it was 12,000. Columbus was really, really wrong – and had to have been really, really sure of himself to ignore the wisdom of all the scholars in his time; he’d have been committing suicide if he was wrong.

I don’t know about you, but that strikes me as just downright odd. Columbus had almost no support for his belief about the size of the Earth, yet he was willing to put his life on the line to prove it. I’d love to know why.

The best theory that I have is that Columbus, somehow, knew that the Americas were there before selling out – or at least that there was land 3,000 miles to the west. That would at least explain why he believed the Earth was so small, and he was not, after all, the first European to get actually get there by a long shot. But even if that’s the case, it begs the question of how exactly he knew this and what made him so sure of what he was told.

It’s a bit of a mystery that I think has been overlooked. I’d love if anyone had any additional insight into it. Any thoughts?


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