My reference is "The Moon Illusion" by L. Kaufman and I. Rock in Scientific
American July 1962.
The problem does exist only in our heads. Stand on your head or bend over
and view the moon through your legs and it disappears.
The distortions due to variable refraction at sunset can be spectacular. I
have seen pear, mushroom and squash shaped suns. The average refraction
correction noted by Roger Sinnott, 34 minutes or 1 sun diameter can be
quite variable, particularity with inversion conditions. A friend who is an
amateur astronomer bought a ranch well out on the bald prairie where the
lights of Calgary were below the horizon. In the winter, the colder air
caused more refraction and the lights of the city popped up and spoiled his
view. He moved back east.
Roger Bailey
At 10:32 AM 3/24/98 MET, Wolfgang R. Dick wrote:
>> 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.
>
>This explanation of the effect is often repeated. However, there are
scientific
>publications stating that it is a psychological/physiological effect. Our
>system of vision (eyes + brain) is such that the real dimensions are changed
>depending on the direction of viewing. That's why we estimate angles more
>precisely near the zenith than near the horizon. It does not have to do with
>the fact wether there are things for comparison or not. This physiological
>effect can be measured with the help of artificial objects. I will see wether
>I can find references.
>
>Wolfgang R. Dick
>
