why is the sky blue?

Answer 1

idk... but i heard from a tv show its because the ocean reflects off of it.. lol.. jk...
it's because sun reflects of molecules.. well i think that's rite..

Answer 2

My! This IS a popular question today!

This question has been asked over 5000 times, and I've prepared a simple answer, without too much science:

The correct answer is that the blue light is scattered by the air molecules in the atmosphere (referred to as Rayleigh scattering). The blue wavelength is scattered more, because the scatteing effect increases with the inverse of the fourth power of the incident wavelength.
OK, but I've known science graduates who don't understand what this means.
Here's my attempt at an answer without too much physics:

I think most people know that sunlight is made up of light of several different wavelengths, and can be split up into the colours of the rainbow. Blue light has the shorter wavelength, and red the longest wavelength.

When sunlight hits the molecules in the atmosphere, the light strikes the molecules and is absorbed. The molecules vibrate and and give off, or 're-emit' the light. Because the molecules vibrate in all directions, the light is emitted in all directions (called 'scattering'). The molecules in the air are much smaller than the wavelength of visible light, but because the blue wavelength is shorter and more energetic, it reacts much more with the air molecules than the red and yellow wavelengths; which tend to pass straight through.

Because the blue radiation is re-emitted from the air molecules in all directions, it seems to us looking from the ground that the blue light is coming from everywhere; hence the sky seems blue.

Near sunset, because of the low angle of the sunlight, we see more of the red and yellow wavelendth passing straight through, hence the colours of the setting sun.

BTW: The sky isn't blue because of a reflection of the sea; its the other way round, The blue colour of the sea is a little more complicated, because as well as the water molecules scattering the blue light, the water absorbs more of the red and yellow wavelengths, leaving the blue part of the spectrum, as well as part of the green (which is why deep water can appear bluish-green). This effect is even stronger with ice; which results in the intense blue colour we see if we look down a crevasse in a glacier, or down a hole in the snow made by a ski stock..
My thanks to varoius contributers for correcting me on some details.

For a complete, scientific explqanation, look up 'blue sky' in Wikipedia.

Answer 3

Ok. So, as the white light from the sun travels through the atmosphere, the blue light gets scattered all over because it has a shorter wavelength. The red light waves are more apparant when the sun is at a low angle or if there is alot of atmosphere (more gas in the air). The blue rays are refracted and they dont get all the way through, but the longer red waves do get through the atmosphere, making the sky look more red. It all has to do with wavelengths and the amount (and density) of the atmosphere.

Answer 4

the air is made up of 70% nitrogen, N2. The molecule is the size...small... that it bends or reflects the blue wavelength of light best. Hence, the sky is blue. (At sunset, the air particles are large so the red light gets through.)

Answer 5

Sunlight striking the earth's atmosphere is refracted into the blue spectrum.

Answer 6

the sunlight hitting the earth's atmosphere is refracted into the blue spectrum.

Answer 7

in other words, the chemicals that you see in the sky hapen to be blue.

Answer 8

6,114 hits

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Answer 9

for the same reason that it appears red at dusk

Answer 10

The Creator made it that way.