Why is it that light coming from distant stars gets red-shifted?
547799
The main reason is because of the general expansion of the universe.  \n\nThe best analogy is to imagine a polka-dot balloon.  As you blow up the balloon, all the dots are moving away from each other.  From the point of view of any one of the dots, all the other dots seem to be moving away from it, and the further away a dot is, the faster the dot seems to be moving.\n\nThus with the galaxies in the Universe; as we look at them with our telescopes, it appears that the farther away a galaxy is from us, the faster it is moving away from us.  But actually, all the galaxies including ours are moving away from each other as the Universe expands.\n\nThe red-shifting is part of what's known as the Doppler effect.  You'll easily notice this effect with regard to sound.  As, say, a car with a stuck horn passes by you, you'll hear a higher pitch to the horn as it approaches you and then it lowers as it moves past and away from you.  This is because the car is moving, relative to you, at a significant fraction of the speed of sound; so as the car approaches, the sound waves start to "catch up" with each other, shortening the wavelength and producing a higher tone.  Then as the car moves away from you, the sound waves get "left behind," the wavelength is stretched out and the tone sounds lower.\n\nThe same thing happens with light, though the relative speed has to be much greater in comparison with the speed of light.  The further away a galaxy is from us, the faster it is moving away relative to us, and the light from the stars in that galaxy is red-shifted as the wavelengths are stretched out.  If the stars were moving towards us with the same speed, the wavelengths would be shortened and the light would be blue-shifted.
124314
Actually, this happens only under certain atmospheric conditions, when the air is quite clear. It is because the speed of light in the layers of air near the ground is slower than the speed of light in layers of air above that. Therefore, just like a lens, the light is bent by this gradient in the speed of light. \n\nRefraction of light is a wavelength-dependent phenomenon. The longest wavelengths are bent, or refracted the least. and the shortest wavelengths are bent the most. The reds, yellows and oranges are the long wavelengths, and they will bend the least, and will head off into space. The shorter wavelengths, the blues and greens and violets will be bent down by the atmosphere to be visible at the ground. In fact, the sun is actually below the horizon for the last few minutes of the sunset. The light has to bend around the earth, and the color that gets bent the most includes the short wavelengths. \n\nWhy do we see green in the green flash, and not violet or blue? There is also Rayleigh-Tyndall scattering going on, caused by the small nitrogen and oxygen molecules in the air. The shortest wavelengths are most scattered by the air molecules, and are scattered out of the sunlight, leaving longer wavelengths for us to see. The blues and violets have very short wavelengths, and are therefore scattered the most. (This is the same process that creates blue skies and orange and red suns at sunset). However, in this case, the yellows and reds and oranges are not present in the sunlight as the sun sets below the horizon, but have travelled out into space, so only the greens, blues and violets remain. The blues and violets are scattered away, leaving the green for us to see as a green flash. \n\nA more complete explanation complete with pictures is in the references.\n\nIt is also interesting to note that the moon can also exhibit a green flash, or a green edge (and also a red edge, in a kind of red flash). At the poles, when the sun is barely below the horizon for hours, the green flash can last for hours apparently, according to friends that have seen it.
310583
It's just a light thing.  I've studied this for art more than for science...um, red light is the shortest wavelenth, so it's the first to be filtered out by distance.  If they're far enough away, only the blues and purple wavelengths make it to your eyes.
138271
This question has two different answers depending on how you read it.  The intensity of the light that reaches you will be reduced as you move away from it, but the intensity of the source stays constant.  Its a matter of perspective, so therefore the preson who asked you this question should clarify it for you.  I'd write both answers and explain each.  Your teacher should except that.
1123647
the twinkling of a star is due to the atmospheric refraction of starlight.Star light travels from rarer to denser medium (hot to cold) so the atmosphere bends the star light towards the normal.That's why it appears slightly higher than the actual position of star when viewed from the horizon.\nBut the apparent position of the star doesn't remain stationary as the physical conditions of the atmosphere is always changing.Therefore the apparent position of the star fluctuates and the path of rays commin from the star goes on varying slightly.Thus the star light entering the eye fluctuates (increase or decree_ randomly with time.Due to the light flux entering the eye the star appears brighter sometime, fainter.Thus the fluctuating apparent position of the star gives rise to the twinkling of starts.\nnow u may ask why plants dont twinkle..its box they are not very distant as the stars.Stars can be considered as a point source of light where as the plants can be considered as many source of light such that they nullify the twinkling effect,Hence, turbulent atmosphere is unable to cause sufficient variations of star light entering our eye.
675121
Well, the gravity causes it to elongate and swirl aroud as it approaches the event horizon, kindof like water going down a plug hole. It stretches, so goes through "red shift" - moving towards (or beyond) the red end of the light e-m spectrum.\n\nNot sure what you mean really by this question, but hope the answer helps.
227364
You must realize that this has been asked over 500 times here. Surely when you asked this question you were notified. Why didn't you look at some of those previous questions and answers? I probably have answered this 50 times myself. I have some very careful detailed answers here to that question, if you just look. \n\nIt is called Rayleigh-Tyndall scattering, caused by the small size of the nitrogen and oxygen molecules in the air that scatter the blue out of the sunlight, leaving it more yellowish than it would be otherwise. At sunset, the reddish color is absorbed by the ozone overhead, creating a deep blue. \n\nIf you want more details, look it up.
905280
Light 'dimming' is due to a decrease in the intensity of the light that reaches your eyes. This is different from the waves loosing energy or becoming 'shorter.'\n\nThink of it this way... When you shoot a shotgun, the pellets are very dense, grouped closely together, when the exit the barrel. As they get farther away from the barrel, they get farther away from each other. This is kind of what happens with a decrease in intensity.\n\nHere's another way, one that is more applicable to your question. Think of the surface of a star. It is, roughly, a sphere. To make this simpler, lets just think of the star as a circle. (It may help to draw this out as I'm explaining it) Let's assume that all of the light that is emitted comes straight out of the surface. A way to picture this is to draw straight lines from the center of the circle outwards. Do this for a few lines that start out very close together and are almost going in the same direction. Extend these lines out very far from the center. Do you see how, as they get farther from the center, they get farther away from each other?\n\nYou can also draw a tiny dot some distance away from the circle. This can represent the earth. How many lines that initially start out close together actually intersect this dot? Now can you see why the light gets dimmer? It is because only a small fraction of the light that is sent in our direction actually reaches us.\n\nWhile it is true that light waves do extend forever, they do not exist everywhere. To describe where something is located, you can only talk about how probable it is to be located somewhere. This is a consequence of the Uncertainty Principle.\n\nIf you want to know more, I suggest looking at wikipedia or googling Schroedinger's Equation. There are probably other people who can explain it far better than I could.
676237
For distant galaxies, the speed that they are moving away from us increases with increasing distance. The speed is detected through the red shift of the light that comes from these galaxies. If something is moving away from you, the light from that object will be shifted toward thr red end of the spectrum (towards lower energies) and the degree of shift is related to how fast that object is moving. This is a very different effect than the reddening caused by interstellar dust (which just removes the higher energy light, but does not shift the frequencies).\n\nAnyway, Hubble found that the farther a galaxy is, the more the red shift. This is exactly what was predicted from general relativity as applied to the universe as a whole. It is also important to note that *every* place in the universe would see a similar relation between distance from them and speed of expansion.
925429
Different wavelength (colour) of Light when passed through prism refract (bend) by diferent angles...\nWhen red light is passed .. as it is composed by only on single wavelength, it, as a whole, bends by the same angle..\nSo, there will be a deviation, but no spliiting....\n\nWhite light has many colours super imposed ( made of many wavelength) and hence each component bends by diferent angles ... causing \nwhat is called, Dispersion.of white light
931172
Because we are really close to our star, the sun.  The light from it drowns out the other lights from stars.  The same way a very small light in a room is drowned out by turning on a much larger one.  At night, we are completely turned away from it, so we can now see other lower light sources.
1147922
The expansion of the universe is the main reason. Yes, there are certainly stars in every direction, most of them contained within other galaxies. At extreme ranges (about 13.7-billion light years) those galaxies are moving away from us so fast that their light is effectively red-shifted out of sight.
585869
No, otherwise similar phenomena would be observed on Earth. Redshift is caused by the lengthening of the light waves - the peaks and troughs are at relatively the same place on the wave compared to locally generated light, but the length has been "stretched". The amount it is "stretched" depends on how fast ourselves and the object are moving apart - generally, objects at greater distance are moving apart more rapidly, so we see more shift. If matter caused this, it would be constant.\n\nThe opposite is true of distant matter moving towards us. For example, the galaxy of Andromena is moving towards our galaxy, and the light we see from this experiences "blue shift" - ie, the shortening of the light waves.\n\nIf red shift could be explained by interaction with matter, then we would not see blue shift. Or if both were caused by interactions with matter, they would cancel each other out, or we would see a steady "equilibrium" situation with the stretching, where all light reaching us from distance would be shifted by the same amount.\n\nSo no, nice theory though, keep plugging away, we need people to question these assumptions to further develop and refine the theories, or to disprove them if they are false!
1171568
In our lifetimes it will be purely because of the filtering effects of the atmosphere and clouds. When there is dust, water, chamicals or ice in the atmosphere the colours let through will change, just like putting a coloured scarf over a lamp. \n\nWhen the sun is low in the sky the high frequencies are scattered, allowing more of the red-yellow light to reach us.\n\nAlthough the sun is predicted to change colour and grow, it will be over bilions of years.
368951
Same phenomenon happens when you look through a convex lens or at your reflection in a spoon. Something to do with the movement of light. It bends and shows stuff the other way around. Sorry, it's not my expertise. But that's basically how it happens.
739943
Very simply: Every element when heated gives off a radiation frequency that is specific to itself. When the entire spectrum of light from a star is analyzed, those frequencies representing specific elements are absorbed and show up as dark lines in specific areas. Each star has a unique pattern. After correcting for any red or blue shift ( discuss that another time), the same elements will appear in the same spectral region.
454817
the doppler effect means that if an object is moving away from us the light it is sending out is slightly more red than normal (the wave length is longer)-a red shift, if it is moving towards us the light from it is slightly more blue(wavelength is shorter)- a blue shift. Most of the galaxies we see in space are red shifted so everything is moving away from everything else. This proves that so far the universe is expanding. If gravity gets the better of us and all the galaxies begin to move in on each other then they would be blue shifted. This may well happen in the far off future- we can't tell yet, but Even if this was happening they wouldn't all meet in a 'big crunch' (the opposite of the big bang) for a few billion years so it's not really anything to worry about!