Before everyone gets carried away by the idea that it exists,
let me point out that there is no such thing as "pure white".
There is a conventional locus of points that are considered
to be white when plotted in chromaticity coordinates. This
locus may correspond to the colors of blackbodies at different
temperatures (I'm not absolutely sure of this) and the points
on the white locus are labelled with "color temperatures"
which depend upon the illuminant. Color films are balanced to
take illuminant color temperature into account, which is why
you will see films labeled "daylight" or "tungsten".
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.)