This image (from Hubble) for example shows dust and gas as if back lit. I always have a problem of getting the scale correct when looking at these images, but I assume multiple lighting sources, but I don't know.
Established Member
This image (from Hubble) for example shows dust and gas as if back lit. I always have a problem of getting the scale correct when looking at these images, but I assume multiple lighting sources, but I don't know.
Order of Kilopi
Multiple is a grand understatement.Originally Posted by jlhredshift
Anyway, the particular one you chose to use as an example, has the original B&W images (click on original images at the top of the page).
The B&W shows how some of the image was due to more exposure.
It also looks to me like there is a certain level of surrounding dust that also helps the exposure seem lighter. (I don't know... I'm going by visual)
I don't know at what wavelengths they are portraying, but I can also guess that there is some level of Cosmic Background Radiation that comes into play.
Also; keep in mind that most of the images the public sees are from multiple images enhanced to bring out the various properties. This will take invisible wavelengths and shift them to the visible for viewing.
Established Member
Is it just luck that the "multiple" sources are behind, preferentially, to in front of the nebulae or is there a "system" of some sort involved with the evolution of the nebulae?Multiple is a grand understatement.
Anyway, the particular one you chose to use as an example, has the original B&W images (click on original images at the top of the page).
The B&W shows how some of the image was due to more exposure.
It also looks to me like there is a certain level of surrounding dust that also helps the exposure seem lighter. (I don't know... I'm going by visual)
I don't know at what wavelengths they are portraying, but I can also guess that there is some level of Cosmic Background Radiation that comes into play.
Also; keep in mind that most of the images the public sees are from multiple images enhanced to bring out the various properties. This will take invisible wavelengths and shift them to the visible for viewing.
Order of Kilopi
Well; I am not an expert and only going with what I have grasped...
I was speaking of the universe as a whole being behind it. So, when you take the normal picture it is black (which a few of the b&w pix do show). And when you crank up the exposure and start picking non-visible spectrums (spectra?), you start getting everything in the universe becoming more pronounced (Distant pinpoints of light, dust, CMB, random floating atoms).
And; there is a heck of a lot more stuff behind the nebula than between the nebula and the camera, so the in between stuff is a lot less "noisy" (lightwise) than the rest of the universe.
Order of Kilopi
Well, stars condense inside dark nebulae, and then stellar winds disperse the nebula remnant.
When the stellar wind blows out the "front" of the nebula (the part facing us) we see backlit strands and streamers, sometimes with stars visible beyond, sometimes with the stars still tucked out of our line of sight.
(If the far side of the nebula is intact while the front has cleared, we see something like the Orion nebula, with a cluster of stars apparently embedded in an illuminated cavity.)
Grant Hutchison
Established Member
Excellant,Thankyou both. Do we know much about the individual stars that are embedded or about the source of the dust?
Order of Kilopi
I'm sure there are people who know a great deal about both.
But I just reached my limit in my last post.
Grant Hutchison
Established Member
That's OK. I was just sitting thinking about the similarities between Orion and the Eagle nebulae, and that the stars that are part of the system light up the dust randomly from our vantage point and that similar things are going on within the dust. I hadn't thouight of that before. Too bad we can not rewind a time camera and see these systems evolve in a twenty minute version of their life.I'm sure there are people who know a great deal about both.
But I just reached my limit in my last post.
Grant Hutchison
POP BANG BOOM
Order of Kilopi
There is more information at the linked sight. I will guess, for I am weak in this sort of thing, that it is an enhanced image that is somewhat close to true color, perhaps. [Not that it would be bright enough for our eyes to see the color, of course.]
If so, the upper blue region is probably due to Rayleigh Scattering. Blue light, as seen in our sky (night or day), is what is observed. The brightness of the blue region suggests a bright star, or stars, are illuminating it and, likely, are contributors to the dispersion of the foreground regions.
It is my understanding ebryonic regions create large blue stars first. These will produce some interesting images. I assume the Eagle might be one of them.
We know time flies, we just can't see its wings.
Banned
The irony is how much is out there we don't see because it isn't backlit. Or producing light.
Order of Kilopi
Yeah it is really dark out there no matter where you look.
Order of Kilopi
The Eagle nebula is back-lit (and front-lit and side-lit) by the hot young early stars of the embryonic cluster that is forming from the nebula. The blue is probably an emission nebula caused by UV from the stars.
Order of Kilopi
Why do you think the blue region is an emission nebula and not a reflection nebula?
We know time flies, we just can't see its wings.
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