Why do we see the sky as Blue, and not Blackness of outer space?
929659
reflection of light\n\nDuring daylight the sky has the appearance of a deep blue surface, but this is the result of the air scattering sunlight. [1] There is no "blue object" above the earth in any normal sense, so it is hard to say what object the sky is. The sky is thus sometimes defined as the denser gaseous zone of a planet's atmosphere. At night the sky has the appearance of a black surface or region scattered with stars. But if we then say that the sky is the entire visible universe, it would not be the same thing we see during the day.
646815
it's not actually, if you look at the ocean, from the top it is blue becaues it is reflecting the light from the sky.   if you are underwater, it looks blue because the blue light is dispersed the least, meaning that the blue light penetrates farther into the water than the other colors of light.
1048733
The sky is blue partly because air scatters short-wavelength light in preference to longer wavelengths. \nWhere the sunlight is nearly tangent to the Earth's surface, the light's path through the atmosphere is so long that much of the blue and even yellow light is scattered out, leaving the sun rays and the clouds it illuminates red, at sunrise and sunset.\n\nso\n\nAn old weather predicting adage rhythmically states: \n\nRed sky at night, Sailors' delight.\nRed sky in morning, Sailors take warning. \n\nHumidity in the air is indicated by red skies at sunset-- red sky at night-- or, at sunrise-- red sky in morning. The forming raindrops scatter the short-wavelength blue light so that only the long-wavelength red light reaches the observer.
267281
Well.........\n\nThe blue color of the sky is due to Rayleigh scattering. As light moves through the atmosphere, most of the longer wavelengths pass straight through. Little of the red, orange and yellow light is affected by the air. \n\nHowever, much of the shorter wavelength light is absorbed by the gas molecules. The absorbed blue light is then radiated in different directions. It gets scattered all around the sky. Whichever direction you look, some of this scattered blue light reaches you. Since you see the blue light from everywhere overhead, the sky looks blue.
1038358
I answer this question nearly every day.  *sigh*  :) :)\n\nThe blue color of the sky is due to Rayleigh scattering. As light moves through the atmosphere, most of the longer wavelengths pass straight through. Little of the red, orange and yellow light is affected by the air. \n\nHowever, much of the shorter wavelength light is absorbed by the gas molecules. The absorbed blue light is then radiated in different directions. It gets scattered all around the sky. Whichever direction you look, some of this scattered blue light reaches you. Since you see the blue light from everywhere overhead, the sky looks blue. \n\nAs you look closer to the horizon, the sky appears much paler in color. To reach you, the scattered blue light must pass through more air. Some of it gets scattered away again in other directions. Less blue light reaches your eyes. The color of the sky near the horizon appears paler or white.
1056723
The sky is blue due to the way that light is bent, it's called Rayleigh Scattering.  Sunlight is white and white light consists of all colors but when it hits our atmosphere the light is broken up into it's component colors by the particles in the atmosphere.  The shortest wavelengths don't make it through the particles but the blue light does - hence the sky appears blue when in fact it has no color ro it (it is after all, nothing but air and water).\n\nAs others have said - grass is green because of chlorophyll - the chemical in all plants and it just happens to be green.
674370
The simplest way to explain it to a 9 year-old would be simply to say that the blue sky is actually sunlight - but all of the colours of light from the sun can pass through the air except blue, and that the sun scatters this blue light in all directions so that you see blue wherever you look.  This is also the reason why the sun appears yellow - in reality it is white because when you mix all colours together you get white - but when you take the blue light out and scatter it all over the sky, then all of the remaining colors add to give you bright yellow.
1057175
Blue sky is cause the the defraction of blue light in the atmosphere... at night there is no light to defract....
375813
Sky is blue because air is not perfectly transparent.  If you look through many miles of it, it gives a bluish color. [This is another way of saying that blue light is scattered by the atmosphere.] The only direction in which you can look through enough miles of air is upwards.  \n\nClouds are not always white.  Clouds can also turn grey or black and they are made out of the very same water molecules they were before.  It all has to do with how large the particles are, when the cloud is newly formed all the water droplets are very tiny and therefore all light is reflected, ie they look white.  As the tiny droplets glom together into larger pieces of airborne water, light can be absorbed more and more, and the cloud turns darker.
378185
Particles in the air refract the white light of the sun into the spectrum.  The sky is blue because blue gets through the easiest.
398924
Interesting question. Our humans eyes only see blue, but in fact there is a myriad of colors in the sky projected by the sun's rays. I think the other colors are in the ultraviolet spectrum, but I'm not entirely sure
643771
The blue color of the sky is due to Rayleigh scattering. As light moves through the atmosphere, most of the longer wavelengths pass straight through. Little of the red, orange and yellow light is affected by the air. \n\nHowever, much of the shorter wavelength light is absorbed by the gas molecules. The absorbed blue light is then radiated in different directions. It gets scattered all around the sky. Whichever direction you look, some of this scattered blue light reaches you. Since you see the blue light from everywhere overhead, the sky looks blue.
388504
because of tyndall effect as the blue clour as a longer wave length in the spectrum of colours it gets scaterd more in the sky \n\n\nmxwltan\n6 minutes ago\n\n\n\nThe Earth's sky is blue because the air molecules (largely nitrogen\nand oxygen) are much smaller than the wavelength of light. When light\nencounters particles much smaller than its wavelength, the scattered\nintensity is inversely proportional to the 4'th power of the\nwavelength. This is called "Rayleigh scattering," and it means that\nhalf the wavelength is scattered with 2**4 = 16 times more intensity.\nThat's why the sky appears blue: the blue light is scattered some 16\ntimes more strongly than the red light. Rayleigh scattering is also\nthe reason why the setting Sun appears red: the blue light has been\nscattered away from the direct sunlight.\n\nThus, if the atmosphere of another planet is composed of a transparent\ngas or gases whose molecules are much smaller than the wavelength of\nlight, we would, in general, also expect the sky on that planet to\nhave a blue color.\n\nIf you want another color of the sky, you need bigger particles in the\nair. You need something bigger than molecules in the air---dust.\n\nDust particles can be many times larger than air molecules but still\nsmall enough to not fall out to the ground. If the dust particles are\nmuch larger than the wavelength of light, the scattered light will be\nneutral in color (i.e., white or gray)---this also happens in clouds\nhere on Earth, which consist of water droplets. If the dust particles\nare of approximately the same size as the wavelength of light, the\nsituation gets complex, and all sorts of interesting scattering\nphenomena may happen. This happens here on Earth from time to time,\nparticularly in desert areas, where the sky may appear white, brown,\nor some other color. Dust is also responsible for the pinkish sky on\nMars, as seen in the photographs returned from the Viking landers.\n\nIf the atmosphere contains lots of dust, the direct light from the Sun\nor Moon may occasionally get some quite unusual color. Sometimes,\ngreen and blue moons have been reported. These phenomena are quite\nrare though---they happen only "once in a blue moon...." :) The dust\nresponsible for these unusual color phenomena is most often volcanic\nin origin. When El Chicon erupted in 1982, this caused unusually\nstrongly colored sunsets in equatorial areas for more than one year.\nThe much bigger volcanic explosion at Krakatoa, some 110 years ago,\ncaused green and blue moons worldwide for a few years.\n\nOne possible exception to the above discussion is if the clouds on the\nplanet are composed of a strongly colored chemical. This might occur\non Jupiter, where the clouds are thought to contain sulfur, phosphorus,\nand/or various organic chemicals.\n\nIt's also worth pointing out that the light of the planet's primary is\nquite insignificant. Our eyes are highly adaptable to the dominating\nillumination and perceive it as "white," within a quite wide range of\npossible colors. During daytime, we perceive the light from the Sun\n(6000 K) as white, and at night we perceive the light from our\nincandescent lamps (2800 K, like a late, cool M star) as white. Only\nif we put these two lights side-by-side, at comparable intensities,\nwill we perceive a clear color difference.\n\nIf the Sun was a hot star (say of spectral type B), it's likely we\nstill would perceive its light as "white" and the sky's color as blue
357291
the sea and sky is blue because of light refraction\n\nthe sea absorbs the longer wavelenghts of light which are near the red end of the visible spectrum, and reflects blue to our eyes which we see. \n\nthe sky reflects all of the light waves in the particles in the sky, water, CO2, Hydrogen, etc., and as it gets nearer to the earth where we can see, most of the red end of the spectrum has been absorbed and the blue is reflected back to our eyes. \n\nand sometimes there are particles that absorb other parts of the spectrum, which accounts for the colors of sunsets and etc.
92915
The sky appears blue due to the scattering of sunlight by dust particles in the air.\n\nSunlight is comprised of light in different wavelengths and can easily be split with a prism.  The dust particles in the air are of the right size that they scatter blue light preferentially.  As a result, we see the sky blue.\n\nThe sky is black at night simply because there isn't any blue light to be scattered.\n\nIncidentally, moonlight is yellow because that is the generally reflected colour off the moon's surface.  It is reflected light strongly in the yellow waveband. The yellow light is not affected by atmospheric scattering.
771668
It depends on what you mean by "the sky."  Think about it.\n\nWe use the phrase "the sky" as if it were a *thing*, an object that reflects light.   Like saying "the ocean", or "the Grand Canyon."  But we all know that the sky isn't an object.  \n\nInstead, we are looking *through* the atmosphere into space.  As many people point out, the atmosphere scatters short wavelengths of sunlight (blues), giving us the impression that we are seeing blue coming at us from all directions (Rayleigh scattering).  (And BTW, it has nothing to do with reflecting the ocean ... c'mon people ... the sky is still blue in all directions in Montana, far far away from any ocean.)\n\nSo if we think of "the sky" to mean the same thing we think of as the "night sky" ... namely deep space ... then no, the true color of "the sky" is "black" and it is only the intervening atmosphere that is fooling us into thinking we see blue in the daytime.\n\nBut if we think of "the sky" as the atmosphere, then, yes the sky is blue in the day, and completely transparent at night (when there is no sunlight filling the sky with blue).\n\nMyself, I tend to think of "the sky" as the atmosphere ... so I would say yes.\n\nHow's that for an answer?
917666
Why is the sky blue?\n\nhttp://math.ucr.edu/home/baez/physics/General/BlueSky/blue_sky.html\n\nhttp://www.sciencemadesimple.com/sky_blue.html\n\nGood luck.\n\nKevin, Liverpool, England.