April 18, 2005
The myth about Columbus and the shape of the Earth
In his April 3, 2005 New York Times column called It's a Flat World, After All, Thomas Friedman begins:
In 1492 Christopher Columbus set sail for India, going west. He had the Nina, the Pinta and the Santa Maria. He never did find India, but he called the people he met "Indians" and came home and reported to his king and queen: "The world is round."
This is just a throwaway anecdote, to set the frame for another of Friedman's typical banal outpourings of conventional wisdom. (Sorry to offend the many Friedman fans that are out there but I have never understood his appeal. Not only does he not seem to have any original insights but he also comes across as patronizing and condescending, especially towards the people of other countries.)
But this posting is not meant to poke fun at Friedman, as enjoyable as that might be. That is done much better by Matt Taibbi of the NY Press as he reviews Friedman's latest book which bears the name The World is Flat. It is instead intended to address one of my pet peeves, the widespread belief that at the time of Columbus' famous journey, he and almost everyone else believed that the Earth was flat.
This is just not true. So can we all get together and stamp out this myth once and for all?
Thomas Kuhn in his book The Copernican Revolution discusses the early cosmologies and shows quite clearly that the idea of the flat Earth went out very early in recorded history. As early as the seventh century BCE Anaximander of Miletus (624-546 BCE) thought that the Earth was in the shape of a wheel. By the fourth century BCE, most Greek philosophers and astronomers believed in a two-sphere universe, in which the Earth was a tiny sphere, surrounded by a much larger concentric rotating sphere in which the stars were embedded.
The beliefs in the sphericity of the Earth, even back in those early days, were based on careful observations and solid reasoning. The fact that ships moving away had their hulls disappear before the mast, the fact that if you were on high ground, you could see more of the ship than when you were at sea level, the circular edge of the shadow of the Earth on the Moon during lunar eclipses, were all convincing arguments against a flat Earth and educated people of that time accepted them.
In fact, there are references to the measurement of the Earth's circumference that appear in Aristotle's (384-322 BCE) writings but the first complete record of this measurement comes from the Eratosthenes (276-194 BCE), the librarian of Alexandria in what is now Egypt, who arrived at a figure that was only off by about 5% from present day measurements, which is remarkable. He obtained this value from observing that the length of the shadow cast by a vertical stick depended on its latitude.
Aristarchus (310-230 BCE) and others in the third century B.C.E had sophisticated measurements of the sizes of the Moon, the Sun, the various distances between them, etc. and all these things were widely known among educated people.
The idea of using the round Earth to sail westward to India was also suggested by geographer Strabo, who was born around 63 BCE.
All this was about 1,500 years before Columbus.
The idea that Columbus and the Spanish nobility may not have been aware of this knowledge is also a myth. Columbus knew the Earth was round as did the other educated people of Spain. The reason that Columbus found it hard to gain support for his expedition was not because people thought he would fall off the edge of the flat Earth, but because Columbus had come up with a dubious calculation for the radius of the Earth that was quite a bit smaller than the accepted value, and it was suspected that he had fudged the calculation in order to make his trip appear more feasible and worth supporting. If the better values for the radius were adopted, then his ships would not have been able to carry enough provisions to reach India.
So Columbus' arrival in America did not save him from falling off the edge of the Earth, it just saved him and his crew from starvation and death. If America had not been there, his ships would never have been able to make the long trip over the Atlantic and Pacific oceans.
So while it is true that in 1492 there were probably some people who thought that the Earth was flat (as there are probably still people now too), this was not the view of educated people, and definitely not true of Columbus and the people of the Spanish Royal Court.
So why is this myth so resilient? Is it because it makes a dramatic story? Is it still taught in history courses in American schools? Whatever the reason, it is time to put it to rest.
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