http://science.howstuffworks.com/question39.htm Here is something interesting to think about: When you look at the sky at night, it is black, with the stars and the moon forming points of light on that black background. So why is it that, during the day, the sky does not remain black with the sun acting as another point of light? Why does the daytime sky turn a bright blue and the stars disappear? The first thing to recognize is that the sun is an extremely bright source of light -- much brighter than the moon. The second thing to recognize is that the atoms of nitrogen and oxygen in the atmosphere have an effect on the sunlight that passes through them. There is a physical phenomenon called Rayleigh scattering that causes light to scatter when it passes through particles that have a diameter one-tenth that of the wavelength (color) of the light. Sunlight is made up of all different colors of light, but because of the elements in the atmosphere the color blue is scattered much more efficiently than the other colors. So when you look at the sky on a clear day, you can see the sun as a bright disk. The blueness you see everywhere else is all of the atoms in the atmosphere scattering blue light toward you. (Because red light, yellow light, green light and the other colors aren't scattered nearly as well, you see the sky as blue.)
http://www.windows.ucar.edu/tour/link=/kids_space/oceanblue.html When sunlight hits the ocean it is scattered by the water molecules that make up the ocean. Sunlight is made up of all of the colors of the rainbow (red through violet). Water molecules scatter blue light the most. This makes the ocean look blue. Sometimes the ocean doesn't appear blue! Many parts of the ocean look green. This is because the blue we would normally see is mixed with the yellow coloring of floating plants...blue and yellow make green! http://www.letusfindout.com/why-is-the-sun-yellow/ Sun is made up of gases mainly like hydrogen, helium and small amount of other elements like sulphur, magnesium, carbon, neon, iron, oxygen, nickel, chromium and calcium. Temperature on the surface of sun is approximately 5780K giving the sun white color but it often appears yellow to us when we look at the sun from the earth because of the atmospheric scattering of light. When white light coming from the sun towards the earth passes through the atmosphere of earth it scatters the blue light (which is responsible for the sky to appear blue) and is left with red color light which appears to us as yellow. When sun goes down in the west during sunset more blue light is scattered than normal so sun appears to us more dark say orange or red. So it can be said that when we look the sun from the earth it appears yellowish but if we move to the space, out of the atmosphere than we will surely notice a slight change in the color of sun and its brightness too. Some people believe that the appearance of sun is only the interpretation of human eye that the light comes from the sun and strikes our retina visual cortex then starts processing and finally tells brain that the light is yellow in color. Color is detected by photosensitive cells in our eyes which are known as cones and some animals do not have these cones. So it can be possible that they see this light as some what grey but this is not actually proved and we are not sure about it. They have black-white rods in their retina which have high light sensitivity. http://findarticles.com/p/articles/mi_m0EPG/is_n11_v29/ai_17408824 The moon doesn't really change color. It just looks as if it does. That's because the Earth's atmosphere--the layer of air around our planet--plays tricks on moonlight. The light has to go through the atmosphere before it reaches our eyes. When the moon is high in the sky, the light has less atmosphere to go through. Then the moon looks white. But when the moon is low over the horizon, the light passes through more atmosphere (see drawing). That makes the moon look orange. And get this--the more moisture, dust, or even pollution there is in the air, the more orange the moon looks. Here is a handy link just for you: http://www.google.com
Hmmm my kid's havent' asked that since they were six! I honestly never thought about finding out why the sky was blue! Thanks Roman very interesting--you get rep!
Sky is natural thing and it is created by GOD. You never change it colour. There are so many natural things which you can not change its colour.