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pitch black?

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cygnus1

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I've been kind of wondering if intergaltic space is pitch black. The reoson the sky glows is caused by sublinal stars and the zodiacal light. If you were to leave the <br />disk of the solar system you would be treated to a sky twice as black as that visible on earth. My question, is if you were to leave the milky way would you be treated to a sky of complete pitch blackness. I would think so. I<br /> mean there is nothing out there really to glow right?<br />I'm mean even the radiation left from the big bang wouldn't brighten the sky anything away from almost complete darkness. When you are out in the woods in overcast or a deep fog the surroundings are at 300 K and yet it looks completly black. The universe is only 3 K or so. You might say that the light galaxies have been giving off has kind poluted the universe with a diffuse light, but as "soon" as it hits a cold galixy it will<br />start to be transfered out of the visible. Thats why things like spitzer work so well.
 
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nexium

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Between the galaxies, the sky is closer to pitch black than most places inside our galaxy, unless you happen to be close to one of the very rare lighted stars in intergalactic space. I don't think zodial light occurs unless there is a star within about one light year and I don't think the 3 degrees k microwave signal is converted to visable light anywhere in the Universe. Neil
 
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cygnus1

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I don't think that the sky is pitch black in most places inside the milkyway other than in say some giant dust clouds. This is facinating but not what I initially had in mind. The 3K backround would give a tiny amount of light in the visble, exceedingly small but its there. something like .5 K T watt per Hz. Don't ask me how a <br />black body curve gives a linear relationship but it does. Maybee this is just an aproximation. Well in star wars you see x wing fighters flying past a very black sky with<br />stars. Its not like the sky we see even in very remote areas. As I see it the galixies beyond 1 billion LY could<br />be basically ignored interms of scatter. The ones from 100 to 10 million are more complicated. There could be about 10 scater events before the light reaches your eyes. Ofcourse this would just make some galaxy appear brighter. And also make it look bigger. What is the density of intergalitic space. How rarefied does it have to be in order to have a negligible chance of scattering photons as the bounce 10 times between galixies. Well I would have to say that if intergaltic space is a million times more rarified than interstellar space it will scatter a million times less than the galixies would. Therefore intergalatic space would look a million times fainter.
 
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newtonian

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cygnus1 - Intergalactic space is relatively dark. However, there are thousands of galaxies on a sort of river in space heading for a Great Attractor.<br /><br />Besides those rare intergalactic stars Neil refers to, we would also see many of these galaxies - unless we are in a void rather than a river of flowing galaxies. Our universe has bubbles and voids.<br /><br />Even in voids there is the IGM, the intergalactic medium.<br /><br />There is a very interesting article on the IGM in Scientific American:<br /><br />“Scientific American,” 10/02, article entitled “The Emptiest Places,” By Evan Scannapieco, Patrick Petitjean and Tom Broadhurst<br /><br />The interstellar medium is about one atom per cubic centimeter; the intergalactic medium (IGM) is about 10^-5 atom per cubic centimeter.<br /><br />The article shows this medium is very hot, highy ionized and highly magnetized.<br /><br />Much hotter than it once was, btw - the article gives evidence of 3 dramatic transitions of the IGM involving heating.<br /><br />Some of the evidence involves intergalactic light - and the Lyman-alpha forest of lines in spectal analysis of distant quasar light passing through intergalactic gas, etc.
 
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