Eratosthene, the man who calculated the Earth's circumference with just a stick and his brain.

Source

Welcome everybody! today we're going to talk about a famous Greek mathematician who discovered Earth's circumference 2000 years ago. In this article i'm going to tell you how he did it and we're going to learn a little bit about the man himself. So let's get started!

Eratosthene, his early life.

Source

He was born in 276 BC in Cyrene. When he was young he studied at a local gymnasium, but later on he went in Alexandria to study grammar under Callimachus. He also studied philosophy in Athens under Stoic Ariston and Arcesilaus, who was head of the Platonic Academy at that time. Eratosthene contributed a lot to the community by writing Chronographies, which contained a lot of important information about the beginning of the Trojan War. His work led to the pharaoh Ptolemy III Euergetes, which he invited Eratosthene to work as a librarian in Alexandria. He became chief librarian within 5 years. but after a few years, old age caught up with him and he started to lose his eye sight. He could no longer read nor observe and decided to self starve himself to death. He died in Alexandria at the age of 82.

How he calculated the Earth's circumference.

Source

In this day and age we all know that Earth is round, but in Eratosthene's time a lot of people didn't with the exception of a few. His discovery began in Alexandria. Where he was informed that in Syene (a neighboring town) in the local noon, there were no vertical shadows. So he wondered if that would happen in Alexandria too, he took a stick and put it to the ground and there was a shadow. He measured that shadow at 7.2° and came to the conclusion that Earth was curved and using his observations he could figure out the entire of Earth's circumference. He hired a man to pace the distance between Alexandria and Syene, he found out that the distance was 5000 stadia which is about 800 KMs. Using simple mathematics Eratosthene concluded that the Earth's circumference was about 40,000 KM, which it is.

This is how he calculated it.

Conclusion.

Well i think the moral of the story is... Our ancestors are much smarter than we think they were, there are a lot of technology and discoveries that still make us scratch our heads and say "How the hell did they do this?". Well sometimes it's simple and sometimes it's more complicated.

---

---

Thanks for reading everybody! If you liked this article please give it a Upvote, it would help a lot.

---

---