22 Jan 16
2 edits
There is a picture at the top of this link that I query:
http://phys.org/news/2016-01-dark-noodles-lurk-milky.html
If you look at it, the night sky appears to glow rather green in places especially on the right hand side just above the horizon. Is that just false color? If not, where does that green light come from? Is it light pollution? -seems a bit odd for it to be green! Or does parts of the Milky way as we see it in the sky sometimes look greenish and, if so, why?
22 Jan 16
The accuracy of colours in a long exposure night time photo are not to be trusted.
It does look to be atmosphere related, could it be related to the 'green flash'?
https://en.wikipedia.org/wiki/Green_flash
The light appears to be coming from ground sources but that may not be the case.
Certainly, I very much doubt that it has anything to do with the colours of light actually coming from the milky way. A space based picture, or even one taken straight upwards, would not show the greenish tint.
22 Jan 16
1 edit
Originally posted by twhiteheadI have just read that link and I doubt it because it says:
could it be related to the 'green flash'?
https://en.wikipedia.org/wiki/Green_flash
.
"..Green flashes and green rays are optical phenomena that sometimes occur right after sunset or right before sunrise. When the conditions are right, a green spot is visible above the upper rim of the disk of the sun. The green appearance usually lasts for no more than a second or two. Rarely, the green flash can resemble a green ray shooting up from the sunset (or sunrise) point...."
and there is no sun in the picture.
But I believe you that the green tint cannot be from the Milky way itself.
Originally posted by humyThat light is most certainly coming from the ground, most likely a city of some size a distance away. There are also green tinted lights seen right in the middle of the telescopes themselves so the coloring could have come from the photo technique or post production hue and saturation adjustments. I do that a lot with my own photo's.
There is a picture at the top of this link that I query:
http://phys.org/news/2016-01-dark-noodles-lurk-milky.html
If you look at it, the night sky appears to glow rather green in places especially on the right hand side just above the horizon. Is that just false color? If not, where does that green light come from? Is it light pollution? -seems a bit odd ...[text shortened]... Or does parts of the Milky way as we see it in the sky sometimes look greenish and, if so, why?
Eastern Australia is a bit too close to the equator for my first thought: Distant Aurora Borealis.
Maybe Aurora Australis:
http://www.softservenews.com/southern_lights.html
Definite green there. But could you see them from the site of that telescope? I don't have a clue about that one. You might be able to rule that out by the direction the optical scope was aimed. Don't think you would see southern lights if you were pointing your scope due north.
The image doesn't say anything about what direction the camera was recording.
A bit of googling, I see that scope, the 'compact array of Australia' is around 30 degrees south, so it all but rules out southern lights but not totally. If those southern lights had been visible, I would have thought the authors would have mentioned it in the article.
So most likely, a town and the photo was tinkered with.
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25 Jan 16
Originally posted by humyThe green glow is human light pollution.
There is a picture at the top of this link that I query:
http://phys.org/news/2016-01-dark-noodles-lurk-milky.html
If you look at it, the night sky appears to glow rather green in places especially on the right hand side just above the horizon. Is that just false color? If not, where does that green light come from? Is it light pollution? -seems a bit odd ...[text shortened]... Or does parts of the Milky way as we see it in the sky sometimes look greenish and, if so, why?
You see it often in long exposure night pictures.
Street lights do not have much if any blue light in them, but do often have yellow and green. The ubiquitous
sodium light for example looks yellow/orange but actually includes a green light emission band as well.
Green is shorter wavelength and scatters more.
25 Jan 16
Originally posted by googlefudgeYes, I mentioned the lights under the dishes also have a greenish cast. That's what tilted it to human lights of some town in the distance.
The green glow is human light pollution.
You see it often in long exposure night pictures.
Street lights do not have much if any blue light in them, but do often have yellow and green. The ubiquitous
sodium light for example looks yellow/orange but actually includes a green light emission band as well.
Green is shorter wavelength and scatters more.
26 Jan 16
Originally posted by googlefudgeYes, that makes a lot of sense to me. That explains to me why mainly green light in particular may be seen being scattered from the night sky in particular. Thanks.
...
Street lights do not have much if any blue light in them, but do often have yellow and green.
...
Green is shorter wavelength and scatters more.