I apologise if this has been addressed recently, I didn't find any posts about this:
I am curious how the sunsets can be explained as "too far to see" or an "optical illusion" if the sun (at ~3000 miles high) can never get lower than ~7 degrees above the horizon. That is assuming the greatest possible distance, if you're at the "ice wall" and the sun is directly above the other side ice wall 25,000 miles away. This can't be compared to power lines fading down to nothing, its a completely different scale.
More realistically, and according to models I see here, the sun seldom gets lower than ~9 degrees above the horizon (this assumes you are standing at the "ice wall" and the sun is at the equator opposite from you.). I get these numbers from basic trigonometry: arctan(3000/(3/4*24900))=9.12 degrees.
At this distance, the sun would have an angular diameter close to 6 minutes across (or .1 degree), easily viewable with the human eye ~9 degrees above the horizon.
Even if we were to assume the "spotlight" theory, the 32 mile wide underside of the sun, even 3/4 the diameter of the earth away would still be within the scope of vision of the human eye at just under 1 minute of arc (The human eye has a resolution of about 50 arcseconds.). Again this would be at ~9 degrees above the horizon, not smashed up next to it.
These calculations were done with the small angle formula found on wiki.
Any/All FE believer(s) are welcome to respond, as well as RE believers to add something I may have forgotten.