Why is the sky blue, but when you see pictures from outer space, it looks black all around.?
369741
The sky is blue to us beause of Rayleigh scattering.  From outer space, you don't have that atmosphere effect, so it's black.
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.
80014
The nitrogen and the oxygen molecules in the air have the right dimensions to scatter blue light, but other colors pass through with little problem. So this causes the sky to look blue. \n\n(whitish sunlight)-(blue light scattered)= (yellowish sunlight)\n\nAs the sun sets (or rises), the sunlight passes through more air, and more blue light gets scatted, so the sunlight looks closer to orange or red\n\n(whitish sunlight)-(even more blue light scattered)=(red or orange sunlight)
389534
it is 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 \n 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
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.
64367
Actually there is no colore\nAnd we see it blue because of light reflex in the sky.
759948
The earth's atmosphere scatters light.  That is why the sky is black at night (no light to scatter).  If you notice that toward the end of the day at sunset the sky turns orange and red. \n\nThat is because of your viewing angle relative to the light passing through the earth's atmosphere.  Due to the angle of the light from the sun relative to your eye at sunset, the light has to pass through more of the earth's atmosphere.  Orange and Red light have larger wavelengths and are able to penetrate the atmosphere, while blue light is not.  \n\nThat is why the sky is blue during the day, the higher energy (shorter wavelengths) of the blue light cannot escape into space through the atmosphere, it scatters making the sky appear blue.
1050973
the blue color of a beautiful sky
585811
This question may be interpreted in two ways.  First, why is the sky not blue at night?  The answer for that is that the sky appears blue during the day because it scatters high energy sunlight.  The atmosphere scatters high energy starlight as well, but there isn't enough of that to make the sky appear blue.\n\nThe other interpretation is why is the sky not totally lit by stars?  That is actually a very important question that was pondered by famous astronomers.  It is called the Dark Night Sky Paradox, or Olbers' Paradox, and was contemplated by such notables as Halley and Kepler as well as the eponymous Heinrich Wilhelm Olbers.  If the universe is of infinite age (as was once assumed) and static, and the stars have had eternity to shine, shouldn't the sky be lit?  \n\nSome people hypothesized that the stars did not appear randomly in all directions.  (So the stars are arranged in straight lines with the Earth at the center so that starlight piles into intervening stars, and there are empty gaps?  Even before Hubble proved that "dark sky" is teeming with distant galaxies, that sounded stupid.)  Others said that dust in the way absorbed starlight.  But after an eternity of absorbing starlight, wouldn't the dust glow as well, and light up the night sky?\n\nThe fact that space is dark turns out to be proof in part that the Universe is not infinite, eternal, and static.  That in fact it had a beginning point in time and space and the Universe is changing.
522607
no the sky is no actually blue, have you noticed that at night you can see space? well thats because during the day the sun ray that come through our hemisphere are hitting against the massive amount of Ocean on our Earth, they do not reflect, but instead refract off the water molecules and transmit into the air, shooting all the way back up to our hemisphere, this gives us the sight of a blue sky.
273384
Those photographs are not at all what you would see with the naked eye- even if you were in a spacecraft nearby.  The pictures are "artificially colored composites" using different colors in the human visual spectrum to represent the different gasses reflecting invisible light frequencies or impossibly subtle detail.\n\nFor a detailed explanation of color in astronomical photos, check out the link below to the Hubble Space Telescope FAQ's.\n\n++++++++\nAnd in response to a few snyde remarks from the peanut gallery, here is a direct quote from hubblesite.org:\n\n"Taking color pictures with the Hubble Space Telescope is much more complex than taking color pictures with a traditional camera. For one thing, Hubble doesn't use color film — in fact, it doesn't use film at all. Rather, its cameras record light from the universe with special electronic detectors. These detectors produce images of the cosmos not in color, but in shades of black and white.\n\nFinished color images are actually combinations of two or more black-and-white exposures to which color has been added during image processing.\n\nThe colors in Hubble images, which are assigned for various reasons, aren't always what we'd see if we were able to visit the imaged objects in a spacecraft. We often use color as a tool, whether it is to enhance an object's detail or to visualize what ordinarily could never be seen by the human eye."\n\nAny other comments?
382450
The 'sky' that you see is not of a solid substance, it is merely molecules in the air scattering light. In this case, most of the time a blue light. At night, the sun disappears and you will see space (the sky has 'disappeared' and now you see beyond the sky), while in actual fact the molecules that create the sky are still there, they are not refracting light. \n\nGravity on earth cannot pull any more particles closer to earth and as such the sky remains staticly placed in the sky forever standing.
143483
Sunlight from the Sun would have to reflect off something in space in order for that region of space not to appear black.  For example the Moon doesn't look black because Sunlight is reflecting off its surface.\n\nSpace is for the most part black since there is an absence of material that can produce or relfect light there.
239803
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\nLink below explains more and has a diagram:
629153
The sky is what people back in the day called what they saw above them because they didnt know what it was..\n\nnow that we know, we know that what we see as blue sky is just refraction of light, and when there is no light ( night ) we just see things out in the universe that reflect light(moon) or emit light ( stars ) \n\nso the sky doesnt really exist, what it is is gases that refract sunlight during the day, and let you see through at night
311003
light is scattered by the suspended water droplets in the air. blue light is preferentially scattered down, thus the sky looks blue
330302
Light is a kind of energy that can travel through space. Light from the sun or a light bulb looks white, but it is really a mixture of many colors. The colors in white light are red, orange, yellow, green, blue and violet. You can see these colors when you look at a rainbow in the sky. \n\nThe sky is filled with air. Air is a mixture of tiny gas molecules and small bits of solid stuff, like dust. \n\nAs sunlight goes through the air, it bumps into the molecules and dust. When light hits a gas molecule, it may bounce off in a different direction. Some colors of light, like red and orange, pass straight through the air. But most of the blue light bounces off in all directions. In this way, the blue light gets scattered all around the sky. \n\nWhen you look up, some of this blue light reaches your eyes from all over the sky. Since you see blue light from everywhere overhead, the sky looks blue. \n\nIn space, there is no air. Because there is nothing for the light to bounce off, it just goes straight. None of the light gets scattered, and the "sky" looks dark and black.