NOTE: I’m not a flat-earther, but have curiosity.
Seeing that famous clip of Carl Sagan explaining the Erathostenes experiment with the shadows of the pillars in Sion and Alexandria a question comes to me, how he knows the position of the shadow in the other site at the same hour? I mean, there were reliable clocks or time measuring methods at that time in order to be sure once traveled from one place to another that he was at the same hour of the day measuring the shadows?
Thanks in advance!!
In: 2
You just have to pick your reference point well
He picked Syene as one of his points because it was known that at solar noon at the summer solstice that there was no shadow at the bottom of the well because the sun shone straight down it.
Solar noon is when the sun is highest in the sky and shadows are shortest, you don’t need a time keep device to find this, just watch your sundial and measure the shadow when its shortest.
Turns out Syene is basically on the tropic of cancer, its about 24 degrees north while the tropic is 23.5 degrees, close enough for his purposes, and the sun was effectively directly overhead of Syene on the summer solstice
So now all he had to do was wait for the summer solstice and measure the length of the shadow of a stick at solar noon(when the shadow is shortest), know the distance to Alexandria (he apparently hired people who specialize in this to find the distance), and do some trig.
Were it not for Syene being located on a tropic he’d have to do additional measurement sets, but you could arrange to do all measurements at solar noon on the summer solstice and everyone could figure out when that is in their location just by watching stick shadows
Latest Answers