In the equator, when the sun forms a right angle with the earth, the tree and its shadow.
eratosthenes wants to know how many stadia south of alexandria this is
I did some digging on this, and while it’s not that it *doesn’t* happen on the equator, it’s more complicated than that:
See also: https://en.wikipedia.org/wiki/Lahaina_Noon
#geography #sun #shadows #neat #the more you know #reply via reblog