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Re: Pure white



The colors perceived by the eye depend among other things on the intensity
of the light. There is an old saying "at night all cats are grey"
indicating the difficulty of perceiving colors under low light conditions.
There is also a difficulty in determining color under high light conditions
as well. Perhaps due to differential saturation of the receptors on the
retina of the eye. The fact that the sun has a yellow cast is easily seen
by viewing it through a neutral density filter such as the type used on
telescopes. There is not doubt about it the sun is yellow when viewed under
these conditions. I haven't tried it yet but as soon as I get the time and
find the filter I will look at a tungsten filament to see if it too looks
yellow. If what I have said is correct it should look even "oranger" than
the sun.


(In 30 years of asking my students about the old saying about cats I have
not once found a student who has ever heard it. It must be a really old
saying.)


At 11:26 AM 4/8/98 -0700, you wrote:
(snip)

I also suspect that the "explanation" of the Sun's alleged
yellow color is a nascent misconception. The only place one
will see a yellow sun is in a child's drawing. That is the
crayon of choice, I think by convention. Please, don't look
at the Sun to check. That can only be harmful, as Galileo
and Pascal learned. If the Sun looks yellow where you live my
advice to you is to leave the area.

Leigh (from BC, where the Sun is shining whitely, and it just
quit snowing an hour ago!)

(I am a recovering Californian, my growth stunted permanently
due to having been raised in LA.)



Jim Riley
Department of Physics
Drury College
Springfield Missouri 65802
(417) 873 7233
e-mail: jriley@lib.drury.edu
fax: (417) 873 7432