24hr Flat Earth Visibility Formula is |Latitude| > 90° – |declination|
Union Glacier in December
An observer at -80°S such as Union Glacier in December (-23°) will see a 24hr Sun because the formula holds for true.
|-80°| > 90° – |-23°|
80° > 90°-23°
80 > 67
true
United States in December
An observer at 45°N such as United States in December (-23°) will not see a 24hr Sun because the formula returns false.
|45°| > 90° – |-23°|
45° > 90° – 23°
45 > 67
false
Manually Determining Celestial Declination through Observation
In our previous video we learned how to determine declination ourselves. That is the sky coordinate of -23° which is the physical location of the Sun. This is determined using the position of your own Sun in December where you live. All of these calculations are done using observer-centric observations you can make yourself and then use the law of perspective to know what the Flat Earth model requires for certain locations.