I have seen claims by the proponents of the flat earth model that what looks like a sunset is actually due to perspective from the sun moving farther away in its "orbit" above the flat earth. This can be shown with simple trigonometry to be completely false; in fact, the trigonometry shows you that in the flat earth model, the sun never gets close to the horizon, and thus viewing a sunset at all proves the flat earth claim false. I have read debunks of the claim, but they focus more on the angular size changes of the Sun that would result from the flat earth model, but I've been surprised that I've yet to find a presentation of the actual trigonometry that shows a flat Earth sunset never happens. I submit the following scenario, with diagram and calculation: Imagine standing on the equator at solar noon on the day of the equinox. In both the globe earth and the flat earth models, the sun will be directly above you. However, this is where the similarity ends. Six hours later, on the globe earth, the sun will have descended to the horizon at a position due West. On the flat earth, the sun will have gone one quarter around its "orbit" and will be seen to be 19.5 degrees above the horizon in a northwest direction. Even when the sun is 12 hours around its orbit, it won't be lower than about 14 degrees (atan(3000/12000)), though magically it will be unobservable and your surroundings will be dark. It is disingenuous to present the setting sun as a "perspective effect" when it is so easy to show how high up in the sky the sun should be as a function of time. This perspective effect only works with objects with a very small ratio of height above the ground to distance from the viewer. I submit this as sufficient to disprove the flat earth model presented above. The setting sun disproves the flat earth model.