[Curiosity File]

Help me out here you guys with math skills
round off the 58" to 5'
1 mile to converge 5'.
The calculations I come up with is 3,168,000. if that's miles, the amount of miles it would take 3,000 to converge with the horizon, if that's correct the idea of perspective is screwed.
I could be way off though. But even it it were only 2 miles instead of 3 million miles off the edge of the flat earth it throws a wrench in the perspective idea.
Somebody else want to give it a try. 

[Bobby Shafto]

You're using ratios, which works.
5:5280
3000:3168000

Using trig, a span of 5' at a distance of 5280' subtends an arc of 0.05426° or 3.25 arcminutes. That's probably not small enough to make the span appear to "merge," but let's just say it is for the sake of illustration.

For a span of 3000 miles to subtend an angle of 0.054°, it would have to be:
3000/tan(0.5426°) ~3,168,000 miles way.

Watch what happens. For 3000 to subtend the stated angle, it must be this far in the distance, per perspective:
1° -> 171,870 miles away
0.5° -> 343,766 miles away
0.25° -> 687,545 miles away
0.125° -> 1,375,100 miles away
0.063° -> 2,728,371 miles away

Every halving of the angular span requires a doubling of the distance. That's why a sun even just 10 miles above a flat earth runs out of real estate before it can drop to 1/60th of a degree elevation.

I mentioned that previously, here and on the Unlit Clouds topic. For a sun to appear to set (or rise) on a flat earth, you've got to have some upward bending of the sun's light. Perspective doesn't cut it.

[stack]

You're using ratios, which works.
5:5280
3000:3168000

Using trig, a span of 5' at a distance of 5280' subtends an arc of 0.05426° or 3.25 arcminutes. That's probably not small enough to make the span appear to "merge," but let's just say it is for the sake of illustration.

For a span of 3000 miles to subtend an angle of 0.054°, it would have to be:
3000/tan(0.5426°) ~3,168,000 miles way.

Watch what happens. For 3000 to subtend the stated angle, it must be this far in the distance, per perspective:
1° -> 171,870 miles away
0.5° -> 343,766 miles away
0.25° -> 687,545 miles away
0.125° -> 1,375,100 miles away
0.063° -> 2,728,371 miles away

Every halving of the angular span requires a doubling of the distance. That's why a sun even just 10 miles above a flat earth runs out of real estate before it can drop to 1/60th of a degree elevation.

I mentioned that previously, here and on the Unlit Clouds topic. For a sun to appear to set (or rise) on a flat earth, you've got to have some upward bending of the sun's light. Perspective doesn't cut it.

Then I guess you would have to factor in the speed of the sun. There's an estimate of around 4 minutes that it takes for the sun to meet the horizon to being below it. Obviously that varies. But given the distances above, the sun would have to be moving away at around 38,347,500 miles per hour, give or take.

[Bobby Shafto]

It's a phenomenon known as alpenglow.  It's fairly common in mountain areas in the "blue hour" before sunrise or after sunset.

Alpenglow (from German: Alpenglühen, Italian: Enrosadira) is an optical phenomenon that appears as a horizontal reddish glow near the horizon opposite of the Sun when the solar disk is just below the horizon. This effect is easily visible when mountains are illuminated, but can also be seen when clouds are lit through backscatter.

Since the sun is below the horizon, there is no direct path for the sunlight to reach the mountain. Unlike sunrise or sunset, the light that causes alpenglow is reflected off airborne precipitation, ice crystals, or particulates in the lower atmosphere. These conditions differentiate between a normal sunrise or sunset, and alpenglow.

I was just told this phenomenon is the Belt of Venus. Sort of a variation on Alpenglow. Never heard of that before.

[ShootingStar]

Excellent image...  looking west just before sunrise.  So the dark grey band hugging the horizon is the shadow of the Earth disappearing westwards.  The pinkish glow just above the dark band is known as the Belt of Venus.  Lovely sight.