the sky is blue, why?
100346
Scattering of Light \nby small particles and molecules in the atmosphere Different from reflection, where radiation is deflected in one direction, some particles and molecules found in the atmosphere have the ability to scatter solar radiation in all directions. The particles/molecules which scatter light are called scatterers and can also include particulates made by human industry. \n\nSelective scattering (or Rayleigh scattering) occurs when certain particles are more effective at scattering a particular wavelength of light. Air molecules, like oxygen and nitrogen for example, are small in size and thus more effective at scattering shorter wavelengths of light (blue and violet). The selective scattering by air molecules is responsible for producing our blue skies on a clear sunny day.
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.
530902
The sky is blue partly because air scatters short-wavelength light in preference to longer wavelengths. Where 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\nIndividual gas molecules are too small to scatter light effectively. However, in a gas, the molecules move more or less independently of each-other, unlike in liquids and solids where the density is determined the molecule's sizes. So the densities of gases, such as pure air, are subject to statistical fluctuations. Significant fluctuations are much more common on a small scale. It is mainly these density fluctuations on a small (tens of nanometers) scale that cause the sky to be blue.
336150
Why is the sky blue ?  Why is the sun yellow ? That is a very logical question guy please, lemme see um cause maybe JUST MAYBE if we do it standing up like you guys, how do I put this umm not a pretty picture right ?  so duh !
539871
in the summer the sky is blue because the atmosphere dullens the color of outer space but in the winter the sky is the color it is because of the water particles that are in the sky
1174306
The refraction (scattering) of light waves from the sun by our atmosphere causes the sky to appear blue.
953737
The answer to part one is "green", and the answer to the second part is "green".\n\nThat is why the sky actually appears blue at noon (blue light is more scattered) and red at sunset (red light is less scattered).
31576
The 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
71027
first of all, to Paranoid Princess:\n\nwhoa, whoa WHOA.  just a minute.  the sky is not blue because there's liquid oxygen in the upper atmosphere.  that's just retarded and you shouldn't go presenting bizzare mis-truths as fact when they *aren't* fact.\n\nhere is a profile of temperatures at various altitudes:\nhttp://www.windows.ucar.edu/tour/link=/earth/images/profile_jpg_image.html\nas you can clearly see the lowest temperature is about -100C.  oxygen liquefies at -182C at normal pressures (reference: http://www.ucc.ie/ucc/depts/chem/dolchem/html/elem/elem008.html ), and even lower temperatures at the low pressures in the upper atmosphere.  PLEASE don't present some bizarre fiction as truth to someone who isn't well-informed enough to know that you're simply fabricating nonsense from thin air.  if you have simply been misled by someone else, at least try to do a marginal amount of research before answering a question on something you don't know much about.\n\nthat said, to the original asker:\n\nthe sky is blue because of a phenomenon called "rayleigh scattering", which occurs because the molecules of air (mostly N2 and O2) happen to be the right size to scatter blue light in all directions.  some of this blue light reaches your eye after being re-scattered again by a second molecule, sometimes all the way across the sky.  \n\nthis is also why the sky turns red at sunset - at low angles, the sunlight has to travel a longer distance through the atmosphere, and by the time it reaches your eye, a lot of the blue light has already been scattered away, leaving yellow orange and red.  (i have yet to hear any explanation of why the sky doesn't turn green between daytime and sunset, though.  still tryin' to figure that one out.)\n\nanyway here are some home/school experiments designed to illustrate rayleigh scattering:\nhttp://www.physics.brown.edu/physics/demopages/Demo/optics/demo/6f4010.htm\nhttp://www.chaosscience.org.uk/dem/public_html/article.php?story=20050222224622239\nhttp://teachers.web.cern.ch/teachers/archiv/HST2002/smallexp/krug/Rayleigh.htm\nhttp://bulldog2.redlands.edu/facultyfolder/deweerd/research/scattering-AJP.pdf\nhttp://www.ktca.org/newtons/9/sky.html\n\nalso, a nice page illustrating rayleigh scattering:\nhttp://hyperphysics.phy-astr.gsu.edu/hbase/atmos/blusky.html\nand a slightly more advanced version:\nhttp://world.std.com/~mmcirvin/bluesky.html
20213
Why is the sky blue? why is the grass green? some things are just unexplainable...
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.
311003
light is scattered by the suspended water droplets in the air. blue light is preferentially scattered down, thus the sky looks blue
128746
The sky is blue because of scattering of the sunlight by the atmosphere. According to Raleigh's law," The amt of scattering is inversely proportional to the 4th power of wavelength".Hence the shorter wavelengths r scattered much more than the longer ones. According to Raleigh's Scattering Law,blue light is scattered to a greater extent than red light. This scattered radiations causes the sky to appear BLUE.
463892
There is no such as the "real" color of the sky. The reason the sky is blue during the day is because the color of the light that the sun shines is white. And as you may know, white is the presence of all color and black is the absence of color.\n\nSo, the white light that the sun emits contains every possible color of light.  Now, each color of light has a different wave length depending on where it is on the color spectrum.  Red light has the longest wave length and blue/violet light have the shortest.  And since blue light has the shortest wave length, you see more of it's waves.\n\n\nsorry... that's the best i can explain it
502400
The 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 \n\nORange of the Moon is simply due to the reflection of light of the sun onto the moon. Its seems orange as simply as the colour of the sun looming on the Moon.
434864
They know the sky is blue because the verrrrrry small particles up there refract blue light from the sun the best, and thus the overall color of the sky is blue.
928427
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. \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. \n\nSOURCES:\nhttp://www.sciencemadesimple.com/sky_blu...\n\nThe Earth's sky is blue because the air molecules (largely nitrogen and oxygen) are much smaller than the wavelength of light. When light encounters particles much smaller than its wavelength, the scattered intensity is inversely proportional to the 4'th power of the wavelength. This is called "Rayleigh scattering," and it means that half 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 times more strongly than the red light. Rayleigh scattering is also the reason why the setting Sun appears red: the blue light has been scattered away from the direct sunlight.\n\nThus, if the atmosphere of another planet is composed of a transparent gas or gases whose molecules are much smaller than the wavelength of light, we would, in general, also expect the sky on that planet to have a blue color.\n\nIf you want another color of the sky, you need bigger particles in the air. You need something bigger than molecules in the air--dust.\n\nDust particles can be many times larger than air molecules but still small enough to not fall out to the ground. If the dust particles are much larger than the wavelength of light, the scattered light will be neutral in color (i.e., white or gray)---this also happens in clouds here on Earth, which consist of water droplets. If the dust particles are of approximately the same size as the wavelength of light, the situation gets complex, and all sorts of interesting scattering phenomena may happen. This happens here on Earth from time to time, particularly in desert areas, where the sky may appear white, brown, or some other color. Dust is also responsible for the pinkish sky on Mars, as seen in the photographs returned from the Viking landers.\n\nIf the atmosphere contains lots of dust, the direct light from the Sun or Moon may occasionally get some quite unusual color. Sometimes, green and blue moons have been reported. These phenomena are quite rare though---they happen only "once in a blue moon...." :) The dust responsible for these unusual color phenomena is most often volcanic in origin. When El Chicon erupted in 1982, this caused unusually strongly colored sunsets in equatorial areas for more than one year. The 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 planet are composed of a strongly colored chemical. This might occur on Jupiter, where the clouds are thought to contain sulfur, phosphorus, and/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 illumination and perceive it as "white," within a quite wide range of possible colors. During daytime, we perceive the light from the Sun (6000 K) as white, and at night we perceive the light from our incandescent lamps (2800 K, like a late, cool M star) as white