The earth being flat?

Question

when (date) did they discover the earth was round

Answer 1

I believe the Greeks were the first ones to actually measure the diameter of the earth.

But no one actually believed the earth was flat even before that. There was too much evidence to the contrary, such as when ships went out to sea, the top part of the masts was the last thing seen.

Answer 2

Pythagoras 570 BCE

Early Greek philosophers alluded to a spherical earth, though with some ambiguity.[2] This idea influenced Pythagoras (b. 570 BCE), who saw harmony in the universe and sought to explain it. He reasoned that Earth and the other planets must be spheres, since the most harmonious geometric solid form is a sphere[1].



Arount 240 BC the greek astronomer Eratosthenes

proved pythagoras right and accurately

Calculated the Earth's Circumference.

It was the Christians that insisted it was flat,

even as Greek scholars continued to insist it was round, having the proof from Eratosthenes.