Light reflected by the Moon
J. Scott Miller
>
> It's common to say that light reflected by the Moon is polarized. What about
> this assertion ?
>
> Why does the moonlight discolour painted surfaces and clothes ?
>
> Thanks for answering !
Reflected light is generally polarized parallel to the "plane" it is
reflected from. We see the Moon by reflected sunlight, so it becomes
polarized upon reflection.
The discoloration may be due to the much weaker amount of light we
receive compared to direct sunlight. If the eye does not receive enough
energy to fire the rods and cones within, it is not going to pick up
color and send proper information to the brain.
--
J. Scott Miller, Program Coordinator jsmi...@homer.louisville.edu
Rauch Memorial Planetarium http://www.louisville.edu/planetarium
University of Louisville
DOMINIQUE LE BRAS
William Keel
: It's common to say that light reflected by the Moon is polarized. What about
: this assertion ?
: Why does the moonlight discolour painted surfaces and clothes ?
: Thanks for answering !
Moonlight is polarized by reflection, like many ordinary daylight
situations (why plarized sunglasses are effective). There were several
Soviet papers on tha matter I once had occasion to look up, which put
the peak polarization at (IIRC) 30%.
However, moonlight doesn't actually change the colors of objects. The
spectrum of moonlight is almost exactly the same as sunlight, as you
can tell from long-exposure pictures taken by moonlight on films that
show little reciprocity failure. However, our color perception is
much less acute at the low levels of moonlight, so that the
visual impression may be rather different.
Bill Keel
Astronomy, University of Alabama
M.C.Harrison
>
> It's common to say that light reflected by the Moon is polarized. What about
> this assertion ?
Can't see why it should be. I can, however, see how some people may have
guessed that it was, by wearing polarised sunglasses.
> Why does the moonlight discolour painted surfaces and clothes ?
In low light conditions, the eye turns off colour vision in favour of
black and white only.