a little bit about how light works. When light travels from the sun

it moves up and down like a wave, similar to the waves you see on the ocean.

Some waves are close together and others are further apart.

The distance between each bump in a wave is called the wavelength

and when all of the different wavelengths travel together l

ight appears white to our eyes. But if you break up sunlight

so that the waves are separated, you will see individual colors.

In fact, every color has its own unique wavelength. Bluish colors have a short wavelength

and move up and down more often than a color like red,

which has a longer wavelength. So if light from the sun contains

all of these different colors, why does the sky appear blue?

Well, it also has to do with the way these waves interact with the atmosphere.

If there were nothing between the sun and our eyes,

the sun would look like a white circle in a black sky.

But the atmosphere gets in the way and changes the way the light behaves.

While the atmosphere may seem like a large empty space,

it is actually made up of a whole bunch of tiny little particles l

ike air molecules, water, and dust. Light waves are tiny too,

so when they finally reach the atmosphere they have a hard time dodging the small particles

in the sky. The shorter wavelengths of light, like blue

and violet, move up and down so much they tend to intereract

with the particles more often than other colors. These colors get bounced around so much

they spread out through the atmosphere and fill the sky.

Even though purple light is also scattering out across the sky,

our eyes are more sensitive to blue light, and so the sky appears more of a bluish color.

Red, yellow, and green colored lightwaves bounce around too,

but not as much, and more of this light passes through.

When these colors are mixed together, they appear a yellowish white,

which is why the sun looks somewhat yellow to our eyes.

So now you know that when you look at a blue sky y

ou are actually looking at a portion of sunlight that has been broken up and scattered

by billions of tiny particles.