The sky is blue — physicists tell us — because blue light in the sun’s rays bends more than red light. But this extra bending, or scattering, applies just as much to violet light, so it is reasonable to ask why the sky isn’t purple. The answer, explained fully for the first time in a new scientific paper, is in the eye of the beholder. “The traditional way that people teach this subject is that sunlight is scattered — more so for shorter wavelengths than for longer ones,” says Glenn Smith, an engineering professor at Georgia Tech. “The other half of the explanation is usually left out: how your eye … Continue reading Michael Schirber