Why is the sky blue?

Graded color of the sky from dark indigo to orange or red at sunset, but we tend to believe that the natural color of the sky is blue. As the sun's light source on the ground, issued a white light, it is astonishing that really always thought that the color of the sky is blue.
And consists of white mix colors of the rainbow (red, orange, yellow, green, blue, indigo, and violet, as it appears in the rainbow) which results from the different lengths of rays constituting the light. The color of the material visible Vintage also the light of the sun with lengths different. Featuring some of the materials ability to absorb light or reversed or refraction in different directions. (With the exception of completely transparent material would allow the passage of light as well as the influence of vision in humans.
The red substance, for example, if exposed to light absorbs all the colors of the spectrum except red, which is reflected. The article reflects some of the red violet and some blue. The black material absorbs all the colors of the rainbow and white Aekshm all.
When the light beam passes through the air, would be inevitably a certain degree of refraction depends on the amount of dust found around him. Break and short-wave spectrum of colors (blue) more than longer wavelengths (red). On clear days, where dust and a few drops of water in the atmosphere will be a reflection of light rays is very limited, so we see the sky light blue. At sunset, where increasing the amount of dust in the air, especially during the harvest, increasing the dispersion of light, especially short-wave blue, so you can keep the yellow and red rays visible on the surface of the earth.
If you land the moon, without atmosphere, surrounded by, looked to the sky is always black, at night and in daylight.