Brian
The moon does not behave like a pure lambertian reflector. At full moon it has a comparitively high reflectance - quite different from that a day before or a day after. The explanation is debatable: and way beyond the scope here, but it's enough to know it is.
"Sunny 16" always crops up as the answer - the only answer - the one that MUST be obeyed..
It's a neat (very plausible) explanation that tends to lead to slight to huge underexposures. Unless the moon is both full and very high in the sky.
Bob
A month ago while visiting my dad in N.M. I had an interesting experience. I heard him prowling around the house in the middle of the night and got up to see what was up. He said "look outside, I think it snowed." Even half awake I knew that couldn't be right - it was too warm. I looked out anyway and - "Holy! crap!" It was very white and, well, snowy looking out there. I opened the front door and stuck my bare foot in the white stuff... . "Huh?" Nothing there. I bent down and felt around - nothing cold and wet. The moon was full and in the high desert the dry, concrete, sand and, gravel landscape looked frosted. I could have read a newspaper.
Al Bedo
Build a Lookaround! The Lookaround Book, 2nd ed. NOW SHIPPING http://www.panoramacamera.us