The laws of perspective in drawing are based on geometry not speculation. Plane (not simple) geometry informs us how to draw things accurately. Plane geometry in perspective is drawing the world as we see it, accurately and realistically.
Plane geometry in perspective
We have vanishing points along a vanishing horizon line in reality not in theory. Flat earth model is consistent with the geometry of perspective, globe earth says we see the edge of a curved earth and dismisses plane geometry as art theory. The problem with that is plane geometry works. How can that which works not be a reality?
A small low sun as it meets the horizon line at a vanishing point to the viewer will disappear from sight as do clouds. The distance in elevation will disappear first, obviously, then bottom to top and sides. You all want to image the space in elevation between sun and earth to always be maintained and is why you think the sun should disappear as a round dot. The sun blends into the horizon line it does not stay above it.
We also have land masses that rise above the horizon and are the reason we see the sun more distinctly set bottom first over land. But as my graph shows, we never see the sun hit the horizon line over land anyway.
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--Dave
1. will the light at the end of the tunnel disappear if you get far enough away?
2. How far away id your physical vanishing point?