The Color of the Sun 177
ILLUSIONS OF THE COLOR OF THE SUN
Persons with normal sight see the sun white, the whitest white there is; but when the sight is imperfect it may appear to be any color in the spectrum-red, blue, green, purple, yellow, etc. In fact, it has even been described by persons with imperfect vision as totally black. The setting sun commonly appears to be red, because of atmospheric conditions; but in many cases these conditions are not such as to change the color, and while this still appears to be red to persons with imperfect vision, to persons with normal vision it ap pears to be white. When the redness of a red sun is an illusion, and not due to atmosphere conditions, its im age on the ground glass of a camera will be white, not red, and the rays focussed with a burning glass will also be white. The same is true of a red moon.
BLIND SPOTS AFTER LOOKING AT THE SUN
After looking at the sun, most people see black or colored spots which may last from a few minutes to a year or longer, but are never permanent. These spots are also illusions, and are not due, as is commonly sup posed, to any organic change in the eye. Even the total blindness which sometimes results, temporarily, from looking at the sun, is only an illusion.
ILLUSIONS OF TWINKLING STARS
The idea that the stars should twinkle has been em bodied in song and story, and is generally accepted as part of the natural order of things; but it can be demon-