Conway Mill Trust

John Tyndall, an Irish scientist, was the first to explain why the sky is blue. In 1859 he discovered that the sun emits a full spectrum of light, but our eyes see the colors blue and red more acutely. The sun’s blue light is scattered by molecules in the air faster than they scatter red light. The sky looks blue during the day because less blue light has been scattered. By the time the sun sets, most of the blue light has been refracted away so the color of the sky tinges with red.