Why is the Sky Blue?

That is a good question.

At some point in everybody’s life they probably asked themselves or someone else that question.  How come the sky isn’t red, or yellow?  Or even white?

Well, let me see if I can help answer that question for you (and for my owners) and give you another fun nature fact.


A beautiful rainbow.

To start with, let’s talk about what color sunlight is.  Sunlight appears to be white or clear, but in fact it is made up of all of the colors of the rainbow.  We know this to be true because of how rainbows are formed.   Rainbows often form when there is sun and rain.  As sunlight passes through the water droplets in the rain the light from the sun gets broken down into all of the colors of the rainbow.


The blue sky above Cascade Canyon in Grand Teton National Park.

Now, let’s think about what is the sky.  The sky is the huge area above the earth that goes up, up, and up all the way until space begins.  Another name for this is the atmosphere.  The atmosphere appears to be empty or sometimes it looks cloudy, but in fact, it  is actually full of lots of different kinds of gases.  One of the main gases, oxygen, is important for animals since we need it to survive.  There is also a small amount of water in the atmosphere, which makes clouds and rain.So, sunlight is made up of all the different colors of the rainbow and the sky is actually full of gas.  When the sunlight goes from the sun to the Earth it runs into all the gas in the sky.  When that happens something really important occurs that explains why the sky is blue.

Like water droplets in rain cause sunlight to break apart and we see all of the different colors of the rainbow, the gases also cause a change to the color of sunlight.  The reds, and oranges pass straight through the gas, but the blues and violets in the sunlight are stopped by the gas.  The gas holds them for a short time and then lets them go, but rather then going in a straight line like the red and orange, the blue gets scattered out in all directions.

The sky is blue because the blue light from sunlight is temporarily absorbed by the gases in the atmosphere.  The gases then release the blue light, which is then scattered in all directions.  Wherever we look up into the sky we see that blue light.

On earth we look up and see the blue coming to us from all directions and so the sky is blue.

I hope this helps you understand why when you look up the sky is blue.