Why is the sky blue?
The sunlight interacting with Earth’s atmosphere makes the sky blue. Sunlight consists of light waves of different wavelengths, each of which is seen as a specific color. When the particles of matter and air molecules in the atmosphere intercept and scatter the white light of the Sun, a larger portion of the blue color in white light is scattered because the blue wavelengths are the shortest. The sky changes color at sunset because, as the Sun drops to the horizon, sunlight has more atmosphere to pass through and loses more of its blue wavelengths. The long wavelengths of orange and red make up more of the sunlight at this distance, and they are the ones likely to be scattered by the air particles.