This man measured the earth’s circumference with a stick & his brain 2,000 years ago

London, Feb 22: Whether the Earth is round or flat sounds to be a juvenile question these days, even though there are people still who believe the earth is flat and even of a donut shape.

However, it is also to be noted that the not the modern-day mathematicians or technocrats but someone who lived on this planet 2,000 years ago deserves the credit of finding out that the earth is indeed round.

Greek mathematician Eratosthenes (276 BC to 194 BC) had it all figured out over 2,000 years ago and that too without any modern equipment at his disposal.

Eratosthenes just had a stick and his brain to measure the circumference of the earth and that he did the job perfectly was confirmed in the 1960s when satellites went into the space and found it to be just over 40,000 kilometres , a figure the Greek had also assumed.

According to an explainer in Business Insider, Eratosthenes, way ahead of his time, discovered that no vertical shadow is cast at noon on the summer solstice at the Egyptian city of Syene (now Aswan).

"Eratosthenes had heard that in Syene, a city south of Alexandria, no vertical shadows were cast at noon on the summer solstice. The sun was directly overhead. He wondered if this were also true in Alexandria," the report said.

"So, on June 21 he planted a stick directly in the ground and waited to see if a shadow would be cast at noon. It turns out there was one. And it measured about 7 degrees."

"Now, if the sun's rays are coming in at the same angle at the same time of day, and a stick in Alexandria is casting a shadow while a stick in Syene is not, it must mean that the Earth's surface is curved. And Eratosthenes probably already knew that."

Pythagoras had floated the idea of the Earth being spherical around 500 BC and it was validated by Aristotle a couple of centuries later. If the Earth was a sphere, Eratosthenes, also the head of the library in Alexandria, could use his observations to measure the planet's circumference.

For the Flat Earthers, Eratosthenes must seem to be not so popular.