Size of sun and moon (sunset -zenith - sunrise)
I took a picture of the sun during sunrise and when it stood in the zenith (by 
duple-exposing). You find this photo on
http://www.hs-bremen.de/planetarium/plasonne.htm
The explanations are in German - sorry. You see that the horizontal diameter is 
the same, the vertical diameter during sunset is smaller because of the effect 
of the differential refraction.
But the size of the moon differs - just the opposite way! During moonrise the 
distance to the moon measures round about 60 times the radius of the earth, 
when 
the moon is in the zenith, the distance measures only 59 times the radius of 
the 
earth. ThatÂ’s why in reality (you can take a photo) the size of the moon in the 
zenith is larger than during moonrise. But the effect is small - up to now I 
got 
no good photo. The same occurs to the sun. But the effect is so vanishing (150 
million km compared with 6370 km) that the size of the sun is always the same. 
The problem exists only in our head. It is not necessary to have something to 
compare near the horizon. Take a mirror and watch the sun - there will be no 
difference in the size during sunrise and when it stand in the zenith.

Dieter Vornholz


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