I noticed that this was never properly answered in previous threads so I will revive it anew. Constellation visibility being specific to your latitude alone disproves the flat earth theory. The farther you are from the equator the closer the constellations are to the horizon until they are no longer visible. You can't see the same constellations in the southern hemisphere that you can see in the northern hemisphere. If the world was indeed flat then you would be able to see the same constellations regardless of your location on Earth. Here are two simplified pictures demonstrating my point. Please attempt to provide reasoning as to why I'm wrong.