The sky looks blue because of Rayleigh scattering.Nspaceplace.nasa.govWhy Is the Sky Blue?Gases and particles in the air scatter sunlight in every direction. Blue light is scattered more than the other colors because it travels as shorter, smaller waves.Sunlight holds every color, and as it passes through the air, nitrogen and oxygen molecules scatter short wavelengths far more strongly than long ones.Wen.wikipedia.orgRayleigh scatteringRayleigh scattering is the scattering of light by particles much smaller than its wavelength. It grows steeply as the wavelength gets shorter, in proportion to 1/λ⁴.That scattered blue light comes at you from every part of the sky, not just from the Sun.Nspaceplace.nasa.govWhy Is the Sky Blue?Gases and particles in the air scatter sunlight in every direction. Blue light is scattered more than the other colors because it travels as shorter, smaller waves.Violet scatters even more, but sunlight carries less of it, some is absorbed high in the atmosphere, and our eyes are less sensitive to it, so the sky reads as blue.Pmath.ucr.eduWhy is the sky blue?If shorter wavelengths scatter most, why isn't the sky violet? The Sun gives off less violet, the upper atmosphere absorbs some of it, and our eyes respond more weakly to it.Near sunset the light crosses far more air on its way to you, so most of the blue is scattered out before it arrives and the reds and oranges are left.Mmetoffice.gov.ukWhy is the sky blue?When the Sun is low, its light passes through much more of the atmosphere. More of the blue is scattered away, leaving the reds and oranges of sunrise and sunset.