Can you see the curvature of the earth from a mountain or from a typical aircraft altitude? Can you see the difference between a Flat Disc Earth and Spherical Earth with your naked eye at various altitudes. Check this model out and you'll see see what you can see, and what you can't - and exactly what each type of earth looks like from various vantage points. Tip: Zoom out first to see what you're looking at. Then zoom into the various platforms at various altitudes, and note how the view of Spherical Earth compares with Flat Disc Earth compares with Infinite DIsc Earth (the gray horizon) from each of them. The model has a sphere and a flat disc, both of the same diameter, both semi-transparent, and both matched up at one point. So you can stand above that point & at one glance see what the view from that altitude would look like on Discworld and on a spherical world, like ours. The gray horizon represents an "Infinite Flat Disc". Look for the point where the disc and the sphere meet, and above that point the model has "platforms" from which you can see the view from a 10,000 foot mountain, from Mount Everest, from a high-flying commercial aircraft, and so on up to low earth orbit and the Space Station.