I have seen the FE animation with the sun&moon spinning around the north pole with a circle of lighted area beneath the sun. I am trying to look at a specific spot on the globe into order to judge the angle to the sun from that point when the terminator line crosses and that spot becomes dark in the evening.
The animations I have seen are of small scale, and I can get a general idea of the direction. I wish to find something more specific. Where is there a resource for this information? I want to enter a location and date in order to get the compass direction to the sunrise/sunset and the times for that date/location. Basically looking for something based on the math behind the map, rather than just the animation.
This formula will calculate the degrees North from due East (sunrise) and due West (sunset) during the vernal and autumnal equinox. It is a simple trigonometric formula based on the Unipolar Flat Earth Map.
=ARCTAN((90 - Latitude)*0.0111)* 57.3
Latitude – Use positive values for latitudes north of the equator and negative values for latitudes south of the equator.
In the Round Earth Model, the sun will rise due East and set due West during the the equinox.
During the equinox:
1) the sun will track directly over the equator.
2) day length is the same (12 hours) over the entire planet.
Source and detail of your formula please.
Formula to calculate sunrise, sunset position for the unipolar flat Earth model.
During the equinox:
1) The sun will follow a path directly over the equator.
2) Day length at all latitudes is 12 hours.
3) Sunrise and sunset for the round Earth model will be due East and due West at all latitudes.
Assume you are 0° N, 0° W – South of Ghana, Africa. (Map below)
At solar noon the sun is directly overhead.
In 6 hours (sunset) the sun will travel to 0° N, 90° W (1/4 the circumference of the equator).
The deviation (N) of the sun from due West at sunset can be calculated by:
Deviation (N) from due West = arctan (D1/D2)
D1= distance from observer to North Pole = 10,000 km
D2 = distance from sunset position (equator) to North Pole = 10,000 km
Arctan (10,000/10,000) = 0.785 radians
= 0.785*57.3
= 45°
D1 was modified to accommodate any latitude.
D1 = (90 - Latitude)*111.1 km
Latitude = latitude of observer (for South latitude used negative value).
111.1 = km/degree latitude (10,000 km / 90°)
D2 = 10,000 km
Deviation (N°) from due West = Arctan ((90 - Latitude) * 111.1 / 10,000) * 57.3
= Arctan ((90 - Latitude) * 0.01111) * 57.3
The same formula can be used to calculate the deviation (N) due East at sunrise.