the Earth is not flat. Flat Earth doctrine is simply the ancients thought that now appears back to brainwash. It's been a lot of evidence suggesting that the Earth is round.
Pfft. The Greeks knew the Earth was a globe, and even managed to calculate its circumference with less than a thousand miles of error.
The following image depicts the Greek dude Eratóstenes.
This is Eratóstenes theory, notice how the Suns rays are in parallel.
This depicts how light from the Sun actually strikes the Earth.
This depicts how the Suns rays look on a globe Earth.
This is how the Sun's rays look on a flat Earth.
The Greeks knew Eratóstenes was full of shit and nobody believed his nonsense, that's what the fucking Greeks knew.