Why is the Sky Blue? Does it Have a Color?

People have always wondered why is the sky blue?

The short answer is it isn't but that it gives off the appearance of blue because during the day, the air in the atmosphere is scattering sunlight. The air scatters short-wavelength light more than longer wavelengths, so what we see is a deep blue.

That is because blue light is at the short wavelength of what we can see and is scattered more in the atmosphere. The light is separated in the atmosphere following something called diffuse sky radiation.

Similarly, at night the sky gives the appearance of being black because of the lack of sunlight to scatter.