Obviously, all those dates should be in the 1400s.
He did? Is this documented anywhere?
That what I was taught in the lower grades, circa late 1950s - early 1960s, up through 3rd grade, right along with George Washington and the cherry tree and such tales. My 4th grade teacher explained to us that this was wrong, and that all educated people in the days of Columbus knew that the earth was round.
I’m pretty sure that it was then also, in 4th grade, that the teacher explained how people could live all over the earth without the people and the oceans on the underside all falling off.
Maybe the idea was that children in then-modern Western education get sophisticated enough by about 4th grade to learn and understand such mysteries.
Dante wrote Divine Comedy in the early 1300’s, in which he pretty clearly lays out a spherical earthly geography, with Mount Purgatory on the opposite side of the globe from Jerusalem. And a comfortable heated shortcut through the center of the Earth to get from here to there.
The problem with the whole Eratosthenes thing is, he didn’t really prove ANYTHING. He assumed the Earth was spherical and was far enough away not to cause parallax. If the Earth is flat, and the sun is close enough you can still have the sun directly overhead in Syene and casting a shadow in Alexandria. Every argument I’ve ever seen that the ancients supposedly used to prove the Earth is a sphere can appear if the Earth is flat. However, the star or the ships at sea or the curveature of the shadow on the moon during an eclipse would act slightly differently if the Earth is a sphere or flat and these differences could be measured.
In the time of Columbus scientist were still mostly still in the believe everything the ancients said mode. And they said the Earth was a sphere.
So why was it still being written, at such later dates, that the curvature of the earth can be seen in its shadow on the moon, and the appearance of ships as they sail past the horizon? – I see several posts above bringing up that question. (ETA: In particular, OP’s paragraph #3.)
Well, even in my own relatively recent youth (relatively recent compared to the days of Columbus, that is), we were still being taught that.
The reasonably clear answer, of course, is to point out to all us impressionable young kiddos that this is something that you can go out and see for your very own self, with your very own eyeballs! In other words, indoctrinating us all in the basic tenet of the Scientific Method!
In 1477 he visited England and Ireland, and may possibly have also visited Iceland at this time. The source is a biography of Columbus written by his son Ferdinand.
If the Earth is flat and circular, and all the land is in the center surrounded by the ocean, then the shadow of the earth on the moon will be circular everywhere except the edges out in the ocean if the moon is far enough away east or west. However the amount of curvature would change depending on where the moon is and that change could be noticed and measured.
Foreshortening can explain ships dissapearing if they get far enough away. The ship gets smaller ans if travels outwards and closer waves would start to cover it from the bottom first. Even a calm sea has swells. It might be a bit more difficult but even this could be tested.
The stars change when traveling north or south and on a flat earth, if the stars were close enough, this would happen too. There would be a profound difference as you went farther north or south and that could be measured.
The ancients, especially the Pythagoreans were system builders. They though the sphere was the perfect shape and designed the earth to be a sphere for that reason. Their proofs were really testable hypothesises.
Yes, I’m aware of England and Ireland. How much evidence is there that he actually went to Iceland (or any other Scandinavian country)?
I mean if we say he possibly went to Iceland where he possibly heard about… then that’s unwarranted speculation. Especially since what he “possibly heard about” happened centuries before he “possibly” went there.
Pffft. Magellen. The first person to prove the Earth was round was Yuri Gagarin.
Poor Elcano gets shafted in these discussions.
There’s also the fact that Columbus sailed south from Spain down to the Canary Islands before crossing the Atlantic and arriving in the Caribbean. This isn’t the route he would have chosen if he was consciously following in the path of Leif Erikson.
That’s only true if you accept “distinctly elliptical” as “circular”.
Once you add together a few easily observable facts: the moon rises at different times on different parts of the planet, eclipses are only total on some parts of the planet and eclipses are always perfectly circular, you are left with a spherical planet.
If the Earth were flat, then the same eclipse would have to be visible everywhere on Earth at the same time since, as you point out, to have even a vaguely circular eclipse, the moon would have to be “far enough away” that the light would be striking the whole moon at near enough the same angle.
If the moon were close enough that a mountain range could make a meaningful difference in the time of moonrise, much less the 12+ hour difference that we actually see, then the shadow of the Earth would be acutely elliptical.
The fact that the sun/moon rise at vastly different times depending on longitude is by itself almost proof that the Earth is round. It can be explained by invoking a rotating disc, a close moon and high mountains. But if the mountains were high enough to generate that effect with a distant sun/moon, then they would be clearly visible to the naked eye. And if the moon is close them ,as you note, the shadow won’t be circular.
Blake, no… all those small things weren’t falsely explained or even known about, at the time of Socrates. They might have predicted your info from their info, but they couldn’t confirm it, not without highly accurate chronographs. They could see data which hinted at the correctness, but they knew the difficulties in being very very sure… There were alternative explanations, possible errors that get in the way … The air might cause lensing. They could see hot air lensing, so the cold air on the ocean might be lensing too. And then the time differences… more lensing ?
Herodotus wrote that many people favoured a spherical earth model before , especially since the Phoenecians travelled down to the south of Africa, and observed the sun well to the North … That ruined flat earth for many…
Its Socrates who uses the shape and curvature of the earth’s shadow on the moon at the lunar eclipse… And the prediction of the eclipses, and all that to show that the the earth is this large, spherical, and the sun is a long long way away.
Perhaps the hold up from Herodotus to Socrates, although it wasn’t so long a time , was only the blood moon… shouldn’t the moon just go black ? Without an explanation for that, they didn’t accept the lunar eclipse data in its entirety… Socrates convinced them to accept the spherical earth. The curve of the earth on the moon … it matched up to the data from the measurement of the sun vs the change in latitude… It was proof, because the mathematical model was proved by precise correlation with the observation. I think socrates explained blood moon (as being normal for light going through the atmosphere, because the sunrise and sunset is also red… and could replicate it in minitature… ) and give good idea as to the scale of lensing from the atmosphere and so on.
Apparently, there was some calendar reform going on around then, as well…
“Freed up some funds” is vaguely disgusting for the source of this wealth. Perhaps it was said cynically; but plunder on such a scale is not an everyday occurrence.
No, Eratosthenes knew the earth was a sphere from the other evidence. He wanted to measure the size of the sphere. As claimed we do not know the actual length of the stadion so we can only guess how close he came. Another source of error was measuring the distance between Alexandria and Syene (modern day Aswan). The method they apparently used was to measure the circumference of a chariot wheel and count the number of revolutions required to go on a straight path from Alexandria to Syene. It is clear that this method is fraught with potential error. Nonetheless he got it pretty well right.
Eratosthenes is better know for having sifted out primes.
The info on Columbus visiting Iceland (called “Ultima Thule” by some) are varied. The 9th/10th Encyclopedia Britannica says he did.
I’ve generally read that he bragged to have visited Iceland but with a good amount of skepticism about it.
It would have been practically impossible for him not to have heard tales of land reachable west of the British Isles.
A source from 1902? I’d like to see something more contemporary before I accept that.
But then, why wouldn’t it have been “practically impossible” for every learned man to have heard of those tales, making CC not such an exception? Or are you just talking about Iceland, not Vinland?
There’s also the theory that Basque fishermen were visiting the grand Banks before Columbus’ voyages, and he knew this…
Way more than you ever want to know… http://www.metrum.org/measures/measurements.htm
From what I read - there were two schools of thought - The Round Earth and Christopher Columbus
Columbus erroneously picks the wrong smaller size diameter for the earth; he takes Marco Polo’s writings and estimates how far east to China; then uses a most convenient definition of “stadia” to estimate that China lies only 3000 miles west from Iberia. Most educated people knew of Erathosthenese calculations and pointed out that the expedition could not sail the necessary 15,000 miles or more to reach China. Spain decided to take a wild chance on Columbus, since Portugal’s command of the circum-Africa route was freezing them out of the opening spice trade.
We’ll never know whether Columbus really visited Iceland. All we know is that his son said he did, and that he story is not implausible, since there was a steady trade between the British Isles and Iceland at the time.
However, I personally am extremely skeptical that he learned anything relevant to his American voyages while there. Columbus didn’t speak Norse and is unlikely to have attended saga recitals with a translator. At best he may have picked up stories of voyages to Greenland, which had ceased less than a century before, but these would have been little different from the legends and tall tales that sailors told of a thousand imaginary lands.