Asked in General and Special Relativity
Why sun appears flattened at sunrise?
July 14, 2009 10:09AM
This is an optical illusion caused by the fact that the sun's rays are passing through the atmosphere at a low angle - hence they pass through a lot more atmosphere relative to when it is high in the sky.
The atmosphere of the earth not only being full of contaminants which tend to disperse the light (the same reason why you see the beam of a torch) but it also can refract and bend the rays due to it being a more dense medium than space.
Combined these have the effect of making the sun appear larger, often a darker hue, and the flattening you see when it rises/sets.