Why do galaxy and galaxy clusters look so colorful?

In summary: Well, of course, since they are striving for cavernous knowledge!In summary, many pictures of galaxies and galaxy clusters have been color enhanced, and it's hard to tell which is which without a forum search.
  • #1
Riotto
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Why do galaxy and galaxy clusters look so colorful?
 
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  • #2
Riotto said:
Why do galaxy and galaxy clusters look so colorful?
And what makes you think they are? Internet photos? Most of those are color enhanced with a combination of overlays from varying frequency ranges shifted to the visible.
 
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  • #3
phinds said:
And what makes you think they are? Internet photos?.

Yes. Are the colours in these pictures completely unreal? I thought there must be some 'atomic physics and spectroscopy theory' behind these beautiful pictures.
 
  • #4
We've had several posts here on PF on exactly this issue. As I recall, there are more true color pics out there than I had expeced but I have no idea how to tell which is which. I suggest a forum search.
 
  • #5
A lot of the photography has to be adjusted to make a meaningful image to a human.
X ray images and radio images are not comprehensible to us without that, other than just as numerical data.
 
  • #6
Riotto said:
Yes. Are the colours in these pictures completely unreal? I thought there must be some 'atomic physics and spectroscopy theory' behind these beautiful pictures.

Many in that set are accurate colours ...

ad6a7af4ec2b041d0b9a74f72cd33507.jpg


06be2886d972b643faa6b54ae196d273.jpg


eea0b03ac7107a9b35630e9deba92a99--planes-group.jpg
many have been severely enhanced and no longer look like reality

2ef6f797d38c9f8e2afef17753304a60--phone-wallpapers-space-iphone-wallpaper.jpg


7ed86a288e4940a29d21981c7d664f68.jpg


74481d2c7ea93431887797e2fe7e42bb--galaxy-universe-the-universe.jpg
and there are also a number of pure artist's impressions there too ... that is, not actual astro images

There is a lot of colour out there with the variety in composition of the gasses in the nebula
the colour/temperature of the star illuminating that gas

Dave
 
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  • #7
I would say that most pictures of galaxies and galaxy clusters are decent approximations of what they would look like if your eye could gather enough light to make them bright enough to see the colors. We don't usually image galaxies with narrowband filters, but with broadband filters, producing images similar to what a normal DSLR camera creates. Still, many of these pictures have had their colors enhanced, so the color contrast wouldn't be as high as you usually see in pictures.

Pictures of nebulas are far more likely to be false color. This is because nebulas often emit light predominantly in a handful of specific wavelengths instead of over a broad spectrum like stars (and galaxies) do. A popular set of narrowband filters used to image nebulas consists of Hydrogen-Alpha (HA), Oxygen-3 (OIII), and Sulfur-2 (SII) filters. HA and SII both pass light in the red part of the visible spectrum, while OIII passes light in the blue-green part. During processing, we often assign these narrowband images a different color than that which they imaged. The so called "Hubble palette" makes SII = red, HA = green, and OIII = blue to produce full color pictures.
 
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  • #8
davenn said:
Many in that set are accurate colours ...

View attachment 206019

View attachment 206020

View attachment 206021many have been severely enhanced and no longer look like reality

View attachment 206022

View attachment 206023

View attachment 206024and there are also a number of pure artist's impressions there too ... that is, not actual astro images

There is a lot of colour out there with the variety in composition of the gasses in the nebula
the colour/temperature of the star illuminating that gas

Dave
Cor! I wish my telescope was as good as yours. :-p
 
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  • #9
sophiecentaur said:
Cor! I wish my telescope as as good as yours. :-p
davenn cheats ... he knows stuff.
 
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  • #10
phinds said:
davenn cheats ... he knows stuff.

hahaha :biggrin:

but I tell you something ... It doesn't take being on PF for very long to realize there are a lot of people that know a lot more stuff ! :smile:
 
  • #11
davenn said:
hahaha :biggrin:

but I tell you something ... It doesn't take being on PF for very long to realize there are a lot of people that know a lot more stuff ! :smile:
All those clever clogs who actually KNOW Maths! V humbling.
 
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  • #12
sophiecentaur said:
All those clever clogs who actually KNOW Maths! V humbling.

Uh huh ... maths and I do not have a good relationship ...
not being able to do the required two first year maths papers at uni is what stopped me finishing my BSc in geology :frown:
 
  • #13
davenn said:
Uh huh ... maths and I do not have a good relationship ...
not being able to do the required two first year maths papers at uni is what stopped me finishing my BSc in geology :frown:

Don't worry. I hear people going into geology usually have a 'rocky' start.
 
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  • #14
Drakkith said:
Don't worry. I hear people going into geology usually have a 'rocky' start.
Followed by in depth study?

DON"T START!
 
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  • #15
sophiecentaur said:
Followed by in depth study?
Well, of course, since they are striving for cavernous knowledge
 
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1. Why do galaxies and galaxy clusters have different colors?

Galaxies and galaxy clusters have different colors due to a combination of factors, including the age and type of stars present, the amount of gas and dust within them, and their distance from Earth. These factors influence the amount and type of light emitted by the galaxies, resulting in a range of colors.

2. How do different colors in galaxies and galaxy clusters relate to their evolution?

The colors of galaxies and galaxy clusters are closely linked to their evolution. For example, younger galaxies tend to have a bluish color due to the presence of hot, young stars, while older galaxies may have a reddish color due to the depletion of gas and fewer young stars. The colors can also indicate the level of star formation and activity within the galaxies, providing insight into their evolutionary stage.

3. Why do some galaxies have a mix of colors?

Some galaxies may appear to have a mix of colors because they contain a variety of stars at different stages of their evolution. For example, a galaxy with a central bulge of older, reddish stars may also have a disk of younger, bluish stars. This mix of colors can also be influenced by interactions with other galaxies, which can trigger bursts of star formation and create a range of colors within the galaxy.

4. Do galaxy clusters always have more color than individual galaxies?

Not necessarily. While galaxy clusters can contain a large number of galaxies, many of these galaxies may be old and have a similar color. On the other hand, individual galaxies can also have a range of colors within them due to their internal structures and processes. Therefore, the amount of color in a galaxy cluster versus an individual galaxy can vary.

5. How do we know the colors of galaxies and galaxy clusters?

We can determine the colors of galaxies and galaxy clusters through various methods, including spectroscopy and imaging. Spectroscopy involves analyzing the light emitted by the galaxies to determine the chemical composition and temperature of the stars, which can then be used to estimate their color. Imaging techniques, such as using filters to isolate specific wavelengths of light, can also provide information about the colors of galaxies and galaxy clusters.

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