Why is the sky blue?

Light appears white but is made up of all the colors of the rainbow. Sunlight is an electromagnetic wave that causes the charged particles within air molecules to oscillate up and down as sunlight passes through the atmosphere. These oscillating particles cause sunlight to scatter in all different directions. The blue component of sunlight has a shorter wavelength and greater frequency than the orange and red components of sunlight. As a result, blue light is scattered with about a ten times greater efficiency than the warmer components of light.

The angle of the sunlight when the sun rises or sets on the horizon produces an opposite effect, and we see spectacular colors of orange and red. Since the moon lacks the earth’s atmosphere, the sky appears dark even when the moon’s surface is bathed in sunlight.