Explore "The Green Girl" by Jack Williamson on Textopian. Read with annotations and highlights.
The only difference between red and blue light is that the waves of the red are about twice as long as the others. There must have been a sort of screen in the ether that somehow intercepted all but a narrow band of frequencies in the red, the other wave-lengths being either canceled or converted into vibrations too long or too short to be perceptible. If there was such a screen, it was slowly altered, so that the lengths of the penetrating waves became shorter and shorter.
In other words, the color of the sky slowly ran through all the colors of the spectrum toward the blue! The sun changed from a vast round blood-ruby to a blazing yellow diamond, flooding the earth with a sodium light! To an emerald, huge and supernally bright, coloring the sea and the sky with a dim and ghastly green radiance! The green melted into a cold and awful blue! The frozen sapphire slowly turned violet! And the violet sun grew soft and dim -- and dim -- until it went out utterly!