Consider this picture...
Its from Apollo 16, and has been marked up
to show the different shadowing effects...
The lunar surface is a fairly bright gray
color. It is known, from the Apollo samples brought back and
analyzed in Houston, to contain a LOT of glass beads, with a
lot of reflective and refractive minerals in it. All of
these materials tend to kick light directly back toward the
source of illumination with very high efficiency, in this
case the sun. This is one reason why the Full Moon is so
much brighter (than other phases) in the night sky; the sun
is "behind" the Earth. The effect of the sunlight hitting
the lunar surface and being reflected back toward the sun
itself creates a "backscatter" that fills in the astronaut's
bright white shadowed suit with excellent "fill-light."
Almost no light at all has seeped into the shadow -- because
it's lying flat on the ground and cannot "see" anything but
black space overhead!
That's the word from the home office,
anyway... but... There's a rock to the of the image - and
seemingly closer to the astronaut taking the picture - that
DOES NOT get any light reflected backwards... nor does any
other shadow-facing object... and the shadow is JET
BLACK - nothing reflects back AT ALL from within the
shadow... nothing. It doesn't make sense to me that
the astronaut can gain from light reflected from the
surface, but nothing else can...
Granted, this isn't the strongest of
arguments... but with every thing else, you start
wondering... well, at least I do.
