[cheerfulgreek]

Originally Posted by MysticCat

Pythagorus, Plato and Aristotle all taught that the earth was spherical. Eratosthenes did a pretty good job of estimating the Earth's circumference sometime around 240 BC. In the second century AD, Claudius Ptolomy plotted the Earth as a globe complete with latitudinal lines measured from the equator and longitudinal lines.

Yep, you forgot to mention Herodotus though. Herodotus pondered this idea too. It was both Pythagoras and Herodotus that pondered that idea. Yep, Arisostle summarized several arguments in support of that view. One of them was based on lunar eclipses. Every now and then, the Moon as it orbits Earth, intercepts the cone shaped shadow that Earth casts in space. Aristotle noted, Earth's shadow on the Moon was always circular. For that to be true, Earth had to be a sphere, because only spheres cast circular shadows via all light sources, from all angles, at all times. If Earth were a flat disk like some people actually still believe to this very day, the shadow would sometimes be oval. And some other times, when Earth's edge faced the Sun, the shadow would be a thin line. Only when the Earth was face on to the Sun would it's shadow cast a circle.