Somewhere around the middle of the 20th century, we started launching satellites into space in order to find out the exact circumference of the Earth, which is 40,030 mk. But a lot earlier, over 2000, one man in Ancient Greece has somehow managed to come up with almost the exact same figure, using just one stick, and of course – his brain.
Maybe you heard for Eratosthenes. He is a mathematician from Ancient Greece and back then he was also the head of the library at Alexandria. He heard that in a city south of Alexandria called Syene, there aren’t any vertical shadows at noon on the summer solstice. That’s when he decided to go there and just plant his stick directly into the ground to see if a shadow would be cast at noon.
So, it appears that there was one after all, and it measured about 7 degrees.
So, if the rays of the sun are coming in at the same angle at the very same time of the day, and a stick in Syene is not casting a shadow while in Alexandria it does, this is enough of a proof that the surface of the Earth is curved. Of course, most probably this ancient man knew that.
Find out more about the rest of this story and this man in the video bellow. It is fascinating how people that didn’t had the same tools we have today, were curious enough to come up with some really amazing and smart solutions, using only the resources they had.