TIL that Eratosthenes paid a guy to walk 800 kilometers to a tower to measure the length of it’s shadow & that’s how we found out the earth was round.
abc.net.au/news/2021-09-05/era…
#til #todayilearned
reddit.com/r/todayilearned/com…
This measurement is more than 2,200 years old, and its accuracy is remarkable
How did Greek librarian Eratosthenes accurately measure the circumference of Earth using a stick, a shadow, and a walk?Gareth Hutchens (ABC News)