Yes Doc Bill, the folks behind that URL might have hit upon the mechanics of the lllusion. Now we should look for an evolutionary advantage for this deceptive portrayal of the external world. I will quote from books and summarize and bring WO'N up to speed.

The rising full moon appears huge on the horizon, although an hour later, when well up, it seems normal in size. This is the moon illusion. Aristotle, Ptolemy, and Confucius all commented on it. At present there exists more than a dozen solutions to the size-distance paradox with each theory having a musing of advocates but so far no consensus.

Most of the distance objects that we see in this world are closer when seen overhead than when seen in the far distance. Clouds are closer than mountains, so it seems natural to assign greater size to the visible objects on the horizon than to those overhead. But the sun and the moon are not in this group, they are exta-terrestrial and are virtually identical in size when on the horizon and when at their zenith. So why does the eye's mind see them as such?