Like the moment the sun is about to vanish goes by so fast. In thirty seconds you can see the last part of the sun go under while the rest of the sunset seems to last way longer.
In: 5
Abstracting from atmospheric phenomena that also influence it….
It’s because of the visible area. **Area = brightness.**
A full Sun is a circle and has the area of pi r squared. Half the sun is obviously 1/2 that.
The upper quarter of the circle (slicing at quarter diametre length) however is not 1/4 of the total area but closer to a 1/6. Then the upper eighth (slicing at eighth diametre length) of the circle is not 1/8 but about 1/13 of the area.
This means when the Sun is 1/8th below the horizon it’s the brightness is roughly 92%. When the Sun is 1/4th below the horizon the brightness is 83%. At half it’s 50%. Then when the Sun is 3/4ths below the horizon the brightness is 17% and when the Sun is 7/8ths below the horizon the brightness is less than 8%.
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