Oldie, but a goodie. Come spend a couple minutes with Carl Sagan as he explains how Eratosthenes figured out the circumference of the earth and that it truly was a sphere!
The pacing is a little slower than we're used to these days, but it's a relaxing five or so minutes. Rebel against the attention economy for a moment this Friday and indulge yourself.
ah but have you considered that uhhh the earth is flat because i said so?