by Ann » Mon Mar 14, 2011 6:17 pm
Mr. Completely wrote:Thanks for this exquisite, aesthetically evocative, intellectually fascinating image, and thanks for supporting this forum!
How close to natural color is this image? I see from the source page
http://www.stern-fan.de/Seiten/galerie_ ... gstar.html:
The colors are mapped to real colors:
light red = H-alpha
blue = blue
dark red= SII
colored stars overlay
In other words, if I were at the distance from this object where this would be the view with the naked eye, how closely would the colors match this image?
Thanks again.
Chris is quite right that you could never see the Flaming Star nebula as red, because our eyes are insensitive to red color and the nebula itself is very faint. And like Chris says, getting closer to a nebula doesn't make it brighter, only bigger. Chris is also right that if our eyes were much, much more sensitive - in which case ordinary daylight would probably blind us - so that we could actually detect color in emission nebulae like the Flaming Star nebula, then they probably still wouldn't look the way they do in photographs. The reason is that the red color of hydrogen and sulphur emission is very deep into the red part of the spectrum, and the red objects that we see around us in daily life are rarely this shade of red. In some ways, you could describe the bright red color of emission nebulosity in photos as "mapped color", not quite the same as it would appear to our eyes, if they were sensitive enough. Don't forget, however, that the deep red Ha light is mixed with some aqua-colored hydrogen beta light, and that mixture of colors might well be visible to super-sensitive eyes as reddish-pink.
As for the Pleiades, the nebulosity around them is much too faint to stimulate color response in human eyes. If our eyes were sensitive enough, though, it wouldn't be difficult to see the blue color of the nebula. In principle, it should not be a lot more difficult to detect the blue color of the nebulosity around the Pleiades for a person with ultra-sensitive color vision than it is for us with ordinary human eyes to detect the blue color of the Earth's sky, because the Earth's sky can be regarded as a sort of reflection nebula, too. The main difference is that the Earth's blue sky is concentrated in a thin layer and very bright, whereas the Pleiades nebulosity is very spread out, very diffuse, and therefore very faint.
Ann
[quote="Mr. Completely"]Thanks for this exquisite, aesthetically evocative, intellectually fascinating image, and thanks for supporting this forum!
How close to natural color is this image? I see from the source page [url]http://www.stern-fan.de/Seiten/galerie_Bild_IC405-Flamingstar.html[/url]:
[quote]The colors are mapped to real colors:
light red = H-alpha
blue = blue
dark red= SII
colored stars overlay[/quote]
In other words, if I were at the distance from this object where this would be the view with the naked eye, how closely would the colors match this image?
Thanks again.[/quote]
Chris is quite right that you could never see the Flaming Star nebula as red, because our eyes are insensitive to red color and the nebula itself is very faint. And like Chris says, getting closer to a nebula doesn't make it brighter, only bigger. Chris is also right that if our eyes were much, much more sensitive - in which case ordinary daylight would probably blind us - so that we could actually detect color in emission nebulae like the Flaming Star nebula, then they probably still wouldn't look the way they do in photographs. The reason is that the red color of hydrogen and sulphur emission is very deep into the red part of the spectrum, and the red objects that we see around us in daily life are rarely this shade of red. In some ways, you could describe the bright red color of emission nebulosity in photos as "mapped color", not quite the same as it would appear to our eyes, if they were sensitive enough. Don't forget, however, that the deep red Ha light is mixed with some aqua-colored hydrogen beta light, and that mixture of colors might well be visible to super-sensitive eyes as reddish-pink.
As for the Pleiades, the nebulosity around them is much too faint to stimulate color response in human eyes. If our eyes were sensitive enough, though, it wouldn't be difficult to see the blue color of the nebula. In principle, it should not be a lot more difficult to detect the blue color of the nebulosity around the Pleiades for a person with ultra-sensitive color vision than it is for us with ordinary human eyes to detect the blue color of the Earth's sky, because the Earth's sky can be regarded as a sort of reflection nebula, too. The main difference is that the Earth's blue sky is concentrated in a thin layer and very bright, whereas the Pleiades nebulosity is very spread out, very diffuse, and therefore very faint.
Ann