Did the Greeks know the world was round?


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I've been thinking a lot of all the stories I took for granted growing up. One that really stuck out was that Columbus already knew the world was round, and so did everyone, because the Greeks not only thought so, they measured the entire circumference of the earth to a large degree of accuracy. I thought it would be fun to apply our literary skepticism to this and see what we can deduce.

I'm not here to prove the earth is or isnt round, full disclosure I'm inclined to think it's round. Instead, I would like to try to show that we probably didn't think it was round until recently and otherwise don't have solid evidence to think otherwise.


This idea traces back to this (obviously Anunaki visitor) named Eratosthenes. This guy was pretty incredible, no doubt a Da Vinci-like polymath (if we are to believe the legend).

He is best known for being the first person to calculate the circumference of the Earth, which he did by comparing altitudes of the mid-day sun at two places a known North-South distance apart. His calculation was remarkably accurate. He was also the first to calculate the tilt of the Earth's axis (again with remarkable accuracy). Additionally, he may have accurately calculated the distance from the Earth to the Sun and invented the leap day.[4] He created the first map of the world, incorporating parallels and meridians based on the available geographic knowledge of his era.

Eratosthenes was the founder of scientific chronology; he endeavored to revise the dates of the chief literary and political events from the conquest of Troy. Eratosthenes dated The Sack of Troy to 1183 BC. In number theory, he introduced the sieve of Eratosthenes, an efficient method of identifying prime numbers.

He was a figure of influence in many fields. According to an entry in the Suda (a 10th-century reference), his critics scorned him, calling him Beta (the second letter of the Greek alphabet) because he always came in second in all his endeavors.[6] Nonetheless, his devotees nicknamed him Pentathlos after the Olympians who were well rounded competitors, for he had proven himself to be knowledgeable in every area of learning. Eratosthenes yearned to understand the complexities of the entire world.

So from Wikipedia we are told this super hero was the originator of Chronology and Geography. Wow! It all starts here folks. But I found this next but particularly interesting.

These works and his great poetic abilities led the pharaoh Ptolemy III Euergetes to seek to place him as a librarian at the Library of Alexandria in the year 245 BC. Eratosthenes, then thirty years old, accepted Ptolemy's invitation and traveled to Alexandria, where he lived for the rest of his life. Within about five years he became Chief Librarian
If you caught my other post, there are some good questions about whether this library was real. If this guy wasn't real, perhaps he was invented as a way to plug some holes and justify future exploration. One problem we uncovered is that it seems talk of this library was pretty quiet until the 1800s! Also, don't forget that people were being killed for suggesting the Earth wasn't the center of creation in those days, perhaps attributing heresy to the Greeks was a way of postulating dangerous ideas?

So let's see what we can find about first the notion that he measured the Earth and whether he was the top dog at the Library of Alexandria.

One question I have is that if he really did measure that the Earth was 10x longer than the known Mediterranean world everyone knew, why wouldn't this spur the Age of Discovery earlier than the Spanish did? Keep this question in mind for now.

We need to track down a work of his called "On the Measurement of the Earth". No problem, right? Except its gone, lost forever! We don't even have a copy or fragments of it. Sorry folks, apparently all we have is a "summary" by another (totally real) super human named Cleomedes. This guy was so amazing he has a crator on the moon named for him. Pretty cool! This makes him at least as important as Stephen Colbert who both have space stuff named after them. On his Wikipedia page it's interesting how scholars have trouble dating him. But who cares, this isn't really about him, let's find his book!

So now we are looking for "On the Circular Motions of the Celestial Bodies" which is a pretty catchy title and reminds me a heck of a lot like stuff Copernicus wrote thousands of years later (right?). It's an interesting book, let's review the summary.

The book for which Cleomedes is known is a fairly basic astronomy textbook in two volumes. His purpose in writing seems to have been as philosophical as it was scientific—he spends an extensive amount of time criticizing the scientific ideas of the Epicureans.

Cleomedes' book is valued primarily for preserving, apparently verbatim, much of Posidonius' writings on astronomy (none of Posidonius' books have survived to the modern day). Cleomedes is accurate in some of his remarks on lunar eclipses, especially his conjecture that the shadow on the Moon suggests a spherical Earth. He also remarks presciently that the absolute size of many stars may exceed that of the Sun (and that the Earth might appear as a very small star, if viewed from the surface of the Sun).

This book is the original source for the well-known story of how Eratosthenes measured the Earth's circumference. Many modern mathematicians and astronomers believe the description to be reasonable (and believe Eratosthenes' achievement to be one of the more impressive accomplishments of ancient astronomy).

Cleomedes deserves credit for the earliest clear statement of the apparent distance explanation of the Sun Illusion or Moon Illusion. He argued that the sun appeared farther away on the horizon than in the zenith, and therefore larger (since its angular size was constant). He attributed this explanation to Posidonius.
We learn that he also preserved the memory of Posidonius as well. He thought eclipses suggest a round earth, and that other stars are other sun's and some could even be bigger than our sun. Pretty impressive! Even more remarkable since the telescope wasn't invented until the 17th century. So let's find this book.

After much searching I determined the earliest copy was from a prolific monk named Maximus Planudes in the 1280s. It bears noting that although he is championed for his preservation and translation efforts, he was also known to "correct" some of the manuscripts he worked on. At this point I could use your help as I haven't been able to verify if his work still survives. My problem is most scholars like to talk about his work on Plutarch so Cleomedes seems to get a backseat. Perhaps it's also because the attribution to Planudes is because of a single signature on the manuscript "Cleomedes, Edinburgh, MS Adv. 18.7.15".


In my search I also came across this manuscript: Aratus’s “Phenomena,” Cleomedes’s “On the Circular Motions of the Celestial Bodies,” and Nichomachus’s “Introduction to Arithmetic”.

The manuscript is written in ancient Greek, on paper, in the same handwriting (except for folio 66 verso), and without book decorations but with drawings, schemes, and tables. The binding is cardboard, with leather spine and corners, and dates from the beginning of the 19th century. Some leaves have been damaged by book pests. An inscription at the top of folio 2 reads tou Vatoupediou, meaning "from the collection of Vatopedi Monastery.” The manuscript was acquired by the Central Scientific Library with the collection of Greek manuscripts described by Ballin de Ballu as early as 1807. It has a stamp "У.Х.", i.e. University of Kharkov. An inscription in the lower margin of folio 2 was painstakingly struck out and is now unreadable. The well-known authority on Greek manuscripts B.L. Fonkich has suggested that the obliterated inscription “Arsenii" could belong to Arsenii Suchanov (1600−68), who in 1653–55 made a trip to Mount Athos, Greece, where he obtained some 500 Greek manuscripts and printed books. This trip was organized on the initiative of Patriarch Nikon of Moscow (1605−81), a well-known church reformer in Russia who wanted to use the acquired books and manuscripts for the purpose of improving Russian prayer books.
And now we're back in the 1800s where I can find a verifiable copy of Cleomedes.

Remember that the Library of Alexandria also started being remembered in the 19th century too.

So either the earliest we know of him is in the 13th century or the 19th. If the 13th, then I would argue that the revelation of this work may indeed have led to eventual exploration into the Atlantic. Problem is, if so then Columbus would know full well that it wouldn't be India unless he thought India stretched 6x longer than the Mediterranean. It would have been reasonable to think there would be more lands before India. This could be worked into my Phoenicians discovered America theory that I'm working on. If this really was written in the year 300bce, why wouldn't people go investigate? If we accept that, then maybe we can also imagine a sea fearing and rich culture did indeed go investigate, then conveniently rediscovered this same work to spur their later descendents in Spain to go back again. That's a different topic though.

As for Eratosthenes being the Librarian at Alexandria I would love your help here. I find tons of websites repeating the claim but have a hard time tracing the origin of this belief.

So did this Greek know how big the earth was? I can't say with confidence that he wasn't made up to justify middle age theories of the universe. One idea I had to justify such fuckery of history is that in order to popularize potentially heretical ideas you would have to attribute them to an ancient philosopher instead and that way you wouldn't burn at the stake.

What do you think?

If this was a middle ages invention, I found a contemporary scientist who did similar measurements and came to a pretty good number

Al-Biruni's Classic Experiment: How to Calculate the Radius of the Earth
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Great research. I think what I always think - let's picture it. In 250 BC, some ancient dude wearing a tunic, got off his horse and figured that he absolutely needed to know:
  • the circumference of the Earth
  • the tilt of the Earth's axis
  • the distance from the Earth to the Sun
  • a bunch of other things as well
Really? All this looks great on paper, and as a study material.

We could talk about the achieved remarkable accuracy of his experiments. Alexandria is 600 miles away from Aswan (Syene at the time). Did he use Skype to communicate between these two locations? Sure enough, it is stated that he knew the position of the Sun in Aswan. Well, may be if Aswan was located on the equator, that could be the case. But Aswan is not even remotely close.

I, personally, think that all this juju with sources, measuring techniques and everything else "ancient" suggests that we are digging in the made up history, looking for authentic info.

Essentially, people appear to be doing similar things within a relatively similar time frame. (building planes, cars, tanks, soda machines, cell phones, etc) Once we start getting those overachieving "geniuses" who jump ahead of their time by hundreds and thousands of years, while the rest of their society lives in the stone age... it's a red flag. We should either look for the real sources of their "discoveries", or look for the times when similar, in this instance, calculations, were being done.


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According to the tale, its not like Eratosthenes was keeping this a secret. He wrote lots of books and was even renown enough to be the Cheif Librarian. The only excuse the historians have is that the Greeks were favoring Aristotle instead. I'm going to explore what Aristotle said, but think about it. They're going to side with Aristotle who basically said the heavens are immutable (I guess it aligns better with mythology?) versus someone who literally calculated (with Roman numerals) the circumference of the earth and also showed the globe of the earth via eclipses?

But then Aristotle was such hot shot they didn't even preserve his works anywhere but Alexandria and if it weren't for the Arabs we wouldn't even have the little we have left of his philosophies. Something doesn't add up here. How can society just forget people like Aristotle and Plato?!


I believe the phantom non-existent time is to blame. There was no thousand years in between there.

Why a person living 2,500 years ago would even come up with an idea of wondering about things like that is beyond me.


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these works dint survive, this tells everthing
also i am sure the earth is round too


I think we may have to take it one step at a time(so to say)

I was going trough the gregorian-Copernicus thing(dates)
When i got to Lilius & Clavius

Then it struk me(i think)
He is from before Copernicus, and he got a celestial globe(in the background)
This must have meant that the earth was allready a globe, and that Copernicus just made it helio-centrical

In other words: i think that most of us(as i did), probably asume that the globe & the heliocentric system are one and the same
And before i knew, i came by a Thread with another eye-opening
Martin behaim and his Erdapfel , also from before Copernicus

So i thought to make a thread about this,.......but just checking for synchronism, i got here.... finding another link true ‘al biruni’ with triangulation How do you calculate distance without mathmatical symbols & high-tech equiptment(i had to put this in here, trying to make an overall picture)

So for me it doesn’t seem to be a real deal to make it helio-centric, when the church allready was assuming that we life on a globe......
And trying to take it one step at a time then, i would like to bring in a question

When did the church started to discreted the bible, by stating that the earth is a globe?


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Eratosthenes initial discovery would be remarkably easy for two people to recreate today in order to veritably confirm or deny flat vs round.

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