Form the site's Wiki;
Although the sun is at all times above the earth's surface, it appears in the morning to ascend from the north-east to the noonday position, and thence to descend and disappear, or set, in the north-west. This phenomenon arises from the operation of a simple and everywhere visible law of perspective. A flock of birds, when passing over a flat or marshy country, always appears to descend is it recedes; and if the flock is extensive, the first bird appears lower or nearer to the horizon than the last, although they are at the same actual altitude above the earth immediately beneath them. When a plane flies away from an observer, without increasing or decreasing its altitude, it appears to gradually approach the horizon. In a long row of lamps, the second, supposing the observer to stand at the beginning of the series, will appear lower than the first; the third lower than the second; and so on to the end of the row; the farthest away always appearing the lowest, although each one has the same altitude; and if such a straight line of lamps could be continued far enough, the lights would at length descend, apparently, to the horizon, or to a level with the eye of the observer. This explains how the sun descends into the horizon as it recedes.
Once the lower part of the Sun meets the horizon line, however, it will intersect with the vanishing point and become lost to human perception as the sun's increasingly shallow path creates a tangent beyond the resolution of the human eye. The vanishing point is created when the perspective lines are angled less than one minute of a degree. Hence, this effectively places the vanishing point a finite distance away from the observer.
Usually it is taught in art schools that the vanishing point is an infinite distance away from the observer, as so:
Fig71.jpg
However, since man cannot perceive infinity due to human limitations, the perspective lines are modified and placed a finite distance away from the observer as so:
Fig75.jpg
This finite distance to the vanishing point is what allows ships to ascend into horizon and disappear as their hulls intersect with the vanishing point. Every receding star and celestial body in the night sky likewise disappears after intersecting with the vanishing point.
Now the real math of an FE World triangle created by the sun and two observers on the ground. Side (a) is the distance from the observer (The observer is Angle C) on the ground at the Equator to the sun directly overhead at 3,150 miles (The Sun is Angle B). Side (b) is the distance on the ground between the two observers of the sun. For this proof, observer 2 (Angle A) can be thought of as standing directly under Polaris, the farthest point it is possible to be from Observer Angle C, which is a distance of 6,300 miles. Side (c) is the distance between observer 2 and the sun, 7,043 miles.
Angle C is 90 degrees as the sun is ALWAYS directly overhead and Observer Angle A is on the same plain as Angle C. Angle A to Angle B is 26.57 degrees. This angle is the MINIMUM angle the sun would appear above the the plain in a FE. The maximum is 90 degrees. Which means the closer Angle A is to Angle C the the Angle to B is STEEPER.
This makes prospective as the reason the sun seems to set below the horizon on a FE plain mathematically impossible. The Sun's angle to ANY observer is NEVER close to the plain/horizon.
The of course in a FE world, the sun, traveling in a circle over the plain would appear in the morning to be traveling SOUTH and in the evening back NORTH as seen from anyplace above the equator.
Here is the online calculator one can use to see FE's use of prospective is fantasy and mathematically impossible;
http://www.csgnetwork.com/righttricalc.html