What causes the color of the sky?

The color of the sky is caused by the scattering of sunlight by molecules and particles in Earth’s atmosphere. When sunlight enters the atmosphere, shorter wavelengths of light, such as blue and violet, are scattered more than longer wavelengths, such as red and yellow. Although violet light is scattered even more than blue, our eyes are more sensitive to blue light, which is why the sky appears blue during the day. At sunrise and sunset, the light passes through more atmosphere, causing the shorter wavelengths to scatter out and leaving the longer wavelengths, which makes the sky appear red or orange.