One of the oldest proofs of the Earth's shape, can be seen from the ground and occurs during every lunar eclipse. The geometry of a lunar eclipse has been known since ancient Greece. When a full Moon occurs in the plane of Earth's orbit, the Moon slowly moves through Earth's shadow. Every time that shadow is seen, its edge is round. Once again, the only solid that always projects a round shadow is a sphere. I see the people here talking about this anti-moon. Where is it? Why can nobody seem to no about it, but you all? Where is your proof that this exists, outside of your imagination?
"The sphericity of the earth is proved by the evidence of … lunar eclipses," Aristotle says. "For whereas in the monthly phases of the moon the segments are of all sorts — straight, gibbous [convex], crescent — in eclipses the dividing line is always rounded. Consequently, if the eclipse is due to the interposition of the earth, the rounded line results from its spherical shape" Of course a frisbee, properly angled, would make a round shadow too. But if the frisbee rotated while the eclipse was in progress, the curvature of its shadow would change. The earth's does not.
The constellations shift relative to the horizon as you move north and south around the globe, something that could only happen if you were standing on a sphere. (You may have to draw a few diagrams to convince yourself of this.) Given sufficient world travel combined with careful observation on your part, the disc hypothesis becomes well-nigh insupportable.
Another simple explanation...
I would also like to hear an explanation on how people have sailed around the world? I really hope you don't dodge these questions, like you have the other's I have seen. I am just interested.