It's safe to say there is a lot about this world we don't know about yet, let alone the universe. However, one thing we know for sure is that the world is round. Because, facts.
Apparently we also knew this long before the first man was sent up into space (and we had, you know, photographic evidence that the world is round) - one of those people in the know was Greek mathematician Eratosthenes, who had it all figured out over 2,000 years ago.
Because Eratosthenes carried out an experiment that not only confirmed the planet's spherical shape, but also allowed him to calculate its circumference. We came to this conclusion in the 60s, when satellites were sent into space and discovered it to be 40,030 km.
However, long before then Eratosthenes arrived at a similar figure using just a stick and his brain. As explained by Business Insider, the attention of the mathematician, who was clearly way ahead of his time, was sparked when he discovered that no vertical shadows were cast at noon on the summer solstice at the city of Syene.
Wondering if it were the same case in Alexandria, where he was based, Eratosthenes stuck a stick in the ground on the same date and lo and behold, there was a shadow and it measured around seven degrees.
This confirmed the speculation that the Earth is round - although he likely already knew that thanks to theories brought to the fore by Pythagoras and further validated by Aristotle a couple of hundred years later.
Using this tidbit and some seriously well-oiled brain power, he came to the conclusion that the seven degree difference of shadow length in Alexandria and Syene meant that the two cities were seven degrees apart on the planet's 360-degrees surface.
So he used his noodle, some mathematics wizardry and managed to work out that the Earth's circumference is roughly 40,000 kilometers, long before anyone had even invented electricity or calculators, let alone space satellites. Pretty clever, right?
Put that in your pipe and smoke it, Flat Earthers.
Featured Image Credit: PA