today is indigenous peoples' day, which means there will likely be some discussion of Christopher Columbus. it is pretty widely known at this point that Columbus was a brutal man who inflicted horrific violence during his time as a colonial governor, but did you know that he was also a fucking moron?
when I was a kid attending American elementary school, the version of "history" I learned sounded something like "everyone thought the world was flat, but Christopher Columbus believed the world was round and that he could reach china by sailing west. he bravely set out to prove it and then he found America." this is a very tidy little narrative that neatly fits him into the myth of the bold American visionary pioneer. the problem, of course, is that basically none of it is true, aside from the fact that Columbus did try to get to east Asia by sailing west and instead ran into an island in the Caribbean
the biggest myth here is "everyone thought the world was flat." educated people have known since at least the time of classical antiquity that the earth is spherical, and even a completely uneducated person can stand on a tall hill or on the deck of a ship at sea and observe the curvature of the earth at the horizon. Eratosthenes of Cyrene, a Greek mathematician, geographer, and astronomer recorded the first known calculation of the earth's circumference sometime around the year 240BC, more than a millennia and a half before Columbus's birth. further calculations were recorded throughout the centuries by Greek, Arabic, Indian, and Iranian scholars
one of those scholars was a man named Abū al-ʿAbbās Aḥmad ibn Muḥammad ibn Kathīr al-Farghānī. sometime between 833 and 857 in Baghdad, al-Farghānī wrote an astronomy textbook which included a calculation of earth's circumference. this textbook was translated into Latin in the 12th century and was quite popular and influential among scholars in Europe. the French astronomer Pierre d'Ailly included al-Farghānī's calculations in his own work on cosmology, and it was from d'Ailly that Christopher Columbus learned that al-Farghānī had calculated that one degree of latitude spans 56.67 miles
then Columbus made a very large mistake: he assumed that the miles in al-Farghānī's calculation were Roman miles. al-Farghānī' did not use Roman miles (approximately 1,480 m). he used Arabic miles (approx 1,830m). this meant that when Columbus tried to calculate the circumference of the Earth, his result was 25% smaller than the numbers scholars had been publishing for over a thousand years
Columbus then compounded this mistake with another: he vastly overestimated how large the Eurasian continent is. scholarly consensus in his day largely agreed with Ptolemy's estimate that Eurasia spans 180° longitude. the actual distance, from Spain to Japan is 150° longitude. Columbus estimated that Eurasia spans 225° longitude. based on this wild overestimate, he calculated that it was 2,400 nautical miles (4,400 km) west from the Canary Islands to Japan
it is, in actuality, 10,600 nautical miles (19,600 km) west from the Canary Islands to Japan
and so when Columbus went around to the courts of Europe looking for someone to sponsor a voyage west, the court geographers took a look at the math and said "absolutely not, you will run out of supplies long before you reach anywhere close to Asia"
THAT is why Columbus found no takers. not because people were too backwards to see his vision of a spherical world, but because his math was catastrophically wrong. eventually the Spanish Monarchs did sponsor him, because they figured it was worth risk for the fortunes they stood to make if he was right. and if he's wrong, well, was anyone really going to miss 3 ships, a few dozen men, and one dumbass from Genoa?
which is the incredible works of science and mathematics that were being done in the Arabic region for like a millennia before the big Western European colonization push. The "dark ages" of western Europe are presented as the primary state of the world, when in reality most of the rest of the connected world in that era was in an age of immense scientific advancement and (rightfully) considered Europeans to be disgusting brutish morons.
the absolute coup of American (and presumably a lot of European) history, erasing all the accomplishments of the people who have since been conquered by our empires, acting as though the world didn't truly begin until white people came into world power
