|MLA Citation:||Bloomfield, Louis A. "Question 953"|
How Everything Works 19 Jan 2018. 19 Jan 2018 <http://howeverythingworks.org/print1.php?QNum=953>.
Red sunsets are much more common and they are caused by Rayleigh scattering—the non-resonant scattering of light by particles that are much smaller than the light's wavelength. While Rayleigh scattering is rather weak, it's weaker for long wavelength light (red light) than it is for short wavelength light (violet light). As a result, blue and violet lights are scattered more than red light; making the sky appear blue and the sun and moon appear red, particularly when they are low on the horizon and most of their blue light is scattered away before it reaches your eyes. When there is extra dust in the air, such as after a volcanic eruption, Rayleigh scattering is enhanced and the red sunsets are particularly intense.