Come join us. Light is made up of electromagnetic waves. The distance between 2 crests in this wave is called the wavelength.
White light contains all the colors of the rainbow.
All the colors in white light have different wavelengths. Red light has the longest wavelength. Red light's wavelength is larger than oxygen atoms are big. When red light passed through the atmosphere, its long wavelength causes it to pass through the atmosphere without being scattered. Blue light has a much, much shorter wavelength than red light.