Ok, in the familiar tradition of Calvin and his dad, I believe I must offer the definitive explanation for that problem you described on your blog site about the size of the moon.
You see, it is all really quite simple. The human eye contains what are called "rods" and "cones". Most of the scientific explanations tells us their primary purpose is for color differentiation. What they do not tell us however, is the lesser known function of those elements. In actuality, the "rods" are very similar to magnets. They indeed have a north and a south pole. The "cones" being cone shaped, also have a distinct orientation such that the large end migrates to the bottom when standing in an upright position. Now, when you invert your head, by looking upside down through your legs, you are actually upsetting that delicate balance and alignment of those rods and cones. The rods, with their north pole thrown out of alignment, are scrambling to rearrange themselves into a logical order all the while the cones also are tumbling around interfering with each others natural alignment. This misalignment is what actually causes the distortion in magnification.
This phenomenon also explains why humans generally cannot remember anything before approximately five years of age. When you are born, these rods and cones have absolutely no reference for orientation. As they are adjusting and positioning themselves, your vision fluctuates in and out of focus and magnification, in effect, causing most everything to be out of focus and preventing you from "burning" an image or memory into your brain. This instability period has been shown to take
approximately five years.
This is undoubtedly the correct explanation.