Question about the color of galaxies & nebulae

  1. phinds

    phinds 8,090
    Gold Member

    In images you see on the internet, large cosmological conglomerations of matter are shown in often gorgeous and variegated colors.

    Am I right in assuming that this is ALWAYS the results of applying false colors to show different wavelengths, or do any of them ever actually look that colorful through a powerful telescope? (I know that colors ARE just different visible wavelengths, I'm referring to false coloring to show wavelengths not visible to human eyes)
     
  2. jcsd
  3. Yes it is false colouring. Some stars do look a different colour even to the naked eye but they aren't bright saturated colours. You can see red, blue, even orange and yellow if you have good eyes.
     
  4. phinds

    phinds 8,090
    Gold Member

    Thank you.
     
  5. phinds

    phinds 8,090
    Gold Member

    another question about the color

    Is there any standard for what the kinds of radiation the different false colors represent?
     
  6. Also colors are quite complicated. It's sometimes very difficult to tell the difference between "false colors" and "true colors." If you shoot a room in video and on different stocks of film, things will look different, but none of that is really "false."

    Things will never look that good if you look directly into the telescope because human color sensors cut out at low light levels. You can then ask what the object would look like if you increased the brightness so that your color sensors work, and this gets you in the world that as much art as science.

    Something that is true for planets as much as for people is that a good or bad photographer can make a big, big difference.
     
  7. No it isn't. What colors do you think Galaxies should be - just shades of grey?

    Stars range from deep red to blue in their color, and galaxies are just made of billions of these little colored pixels. Nebula are also colored, because often they are glowing due to ionized hydrogen molecules which emit a strong reddish pink color.

    That doesnt meant you can see a galaxie in color with your own eye, but those colors are not artificially added in post-processing. They are real data collected by the CCD.
     
  8. davenn

    davenn 3,381
    Science Advisor
    Gold Member
    2014 Award

    Thats not entirely correct.... There are plenty of deep space objects up there that have very distinct and deep colouring. That can be captured with any camera film or digital and without any processing whatsoever.
    for example ... a pic my mate and I took on film of the Orion Nebula back on the 1980's

    [​IMG]

    that is REAL colour!!!! nothing false or manuplated !!!

    M42 is so bright that in a decent scope you can even start to pick out the colour quite easily looking through the scope

    some stuff is colourised for temperature or other property measurements but those images are usually pretty obvious

    cheers
    Dave
     

    Attached Files:

    Last edited: May 4, 2011
  9. davenn

    davenn 3,381
    Science Advisor
    Gold Member
    2014 Award

    and if that didnt impress you .... how about this .... ?

    [​IMG]

    also back in the 1980's when he and I were on a serious astrophotography binge

    Edmund Scientific 8" Newtonian reflector scope, Prime Focus, 1000mm f/l 20 minute exposure.


    Dave
     

    Attached Files:

  10. It's just colour because of the 20 minute exposure. To the naked eye in a telescope you will only see black in white. I've seen the orion nebula multiple times in my telescope and it's nothing more than black and white.

    But when you start to take long exposures of the sky the photo sensor is able to recieve more of the "colourized" photons that makes the nebulaes colourful and such.

    Regards, Robin Andersson.
     
  11. davenn

    davenn 3,381
    Science Advisor
    Gold Member
    2014 Award

    incorrect read my post !!! you ARE able to distinctly detect colour in the objects!

    but may for you, if you have a poor or small scope and low to avg or both eyesight

    but regardless of that thats not the query of the OP he was asking if objects really do have colour or are all the images we see in books/online etc false coloured.
    THE ARE indeed full of colour as my un processed photos show


    Dave
     
  12. I disagree. In a large enough telescope you will start to see colors with the naked eye. To me the Orion nebula in my 13" Dob has a distinctly bluish tint. Bright stars in a telescope are clearly colored - Betelgeuse and Arcturus are distinctly orange, and Rigel is clearly blue. Antares is a deep red. What do others see?
     
  13. davenn

    davenn 3,381
    Science Advisor
    Gold Member
    2014 Award

    Thanks for the back up phyzguy,

    thats my experience too with 10 inch and greater scopes and decent dark observing locations
     
  14. Yes I can clearly see colours of stars in my telescope too, but that can be done with the naked eye as well. I have NO experience with a 13" telescope at all. I own a 5" at the moment and that is the largest aperture I've ever observed the night sky so far. So I can't neither say you are wrong or right. However, I do see colours of stars, especially bright stars.

    And of course I see a red-ish tint of Mira variables, and carbon stars of course shows a clear red-ish colour too.

    Regards, Robin Andersson.
     
  15. davenn

    davenn 3,381
    Science Advisor
    Gold Member
    2014 Award

    ok 5" scope, there's the reason you have never seen the hint of colour in nebula :)
    hopefully one day you will get the chance to look through larger instruments

    Even without a scope the red giants in the sky are obviously red.... Betelguese, Antares to name a couple

    Dave
     
  16. A more learned friend of mine says that by using some software you can roll back the colours of red or blue shifted so you see the true colours as long as you know the distance??
     
  17. phinds

    phinds 8,090
    Gold Member

    AH ... when I said "gorgeous and variegated colors" I just assumed that folks would understand that what I MEANT was "gorgeous and variegated colors" but clearly that didn't happen, so here's the kind of thing I mean. Are any of these likely to NOT have false colors?
     

    Attached Files:

  18. The colors for those nebula may be "truer" than you think. The two nebula on the left hand side are emission sources, so they are basically giant neon lights in the sky. So if they look like Las Vegas neon light shows, that's because they are. Those look to be pretty "realistic" because the star colors look right.

    The pink looks to me like hydrogen emission. The blue and red comes from nitrogen and the green is oxygen emission. Take a thin gas pass an electric current through it, volia, the Las Vegas strip.

    The two pictures on the right hand side look like things that were taken in outside of visual range so the colors are arbitrary. The upper right hand side looks like a gamma/x-ray image and the one on the lower RHS looks like it was taken in infrared.
     
    Last edited: May 5, 2011
  19. Whats the yellow glow in the top left, I think its sodium or helium, not sure which one was the paler coloured one
     
  20. Yes, or well maybe it's not false but a mix of both x-ray, infrared light & visual light. Though I know that the picture at bottom right is NOT visible light, it's x-ray (& another wavelength too?).

    I'm sure someone else can confirm this better than I just did...

    Regards, Robin Andersson.
     
  21. phinds

    phinds 8,090
    Gold Member

    Hm ... interesting information all ... thank you.
     
Know someone interested in this topic? Share a link to this question via email, Google+, Twitter, or Facebook