For centuries, the shape of the Earth was a leading topic of thought among philosophers, historians, poets and others — from various civilizations ranging across time.
The question has been definitively settled since the age of space exploration began in the mid-20th century — largely driven by US-Soviet tensions during the Cold War.
Since then, humans have launched satellites into space and determined that — not only is the Earth round — but its exact circumference is 40,030 km.
But more than 2000 years prior, an ancient Greek mathematician came up with nearly the exact same figure — using only a stick and his mind.
That mathematician was Eratosthenes, the head of the library of Alexandria, who calculated Earth’s circumference by putting a stick in the ground.
How did he do it?
In the video below created by Business Insider, narrator Alex Kuzoian explains exactly that.
See the video
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