This shadow thing really isn't that difficult, Santa. You give the impression of being one of those posters who misunderstands things on purpose (I say this after reading both this and your previous strings of posts).

What is a shadow? When you stand in a shadow you can still see things outside of the shadow. This is because the light emanating from some source (sun, lamp, etc.) is bouncing off other objects and being reflected towards your eyes. This is, of course, how we see anything that we ever see. If you stand in the shadow of a building to get out of the heat of the direct sunlight, you can still see what is going on outside the shadow. I'm certain this has happened to you before, even if you didn't notice it.

Here's a little shadow anecdotes from real life (from yesterday, in fact). There I was, relaxing against a tree in Devil's Lake State Park. We had been rock climbing, and I felt like taking a break and reading "A Natural History of Zero." So I was sitting against this tree, and I was in fact completely covered by the shadow of the tree. Before I started reading I spent some time looking out over the lake and the surrounding hills, all of which were illuminated very brightly. Then, deciding it was time to read, I looked down at my book. But I couldn't read it! Staring at the brightly lit countryside had caused my eyes to adjust to bright light, and when I looked down at the book it took several seconds for my eyes to adjust to the comparatively dim surface off of which I wanted to read. This applies nicely to the Armstrong situation. He could see things beyond the shadow nicely, but when he tried to look down into the shadow it was all very dim. Perhaps if he had spent some time staring down into the shadow his eyes would have adjusted. Perhaps it would have taken far longer than it took me yesterday, because of a greater disparity in the relative brightness of the shadowed and directly lit surfaces.

Aporetic
www.polisci.wisc.edu/~rdparrish