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Thread: Colours of pictures

  1. #1
    Join Date
    Jul 2005
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    Colours of pictures

    Perhaps this is a bit of a dumb question; I'm gonna ask it anyway. I like those beautiful photos of stars and such. Also I read some times about false color photos, where there is a blend of different pictures of different spectra of light. And I read something about red-shift and blue-shift where stars coming towards us are more red colored and stars traveling away from us color blue. How does this fit together in pictures of, for instants hubble? the beautiful colors in those pictures, is this real? when we would travel to those star formations, do we see those colors like that or not? And a red giant star, is this truly a red colored sun?

  2. #2
    Join Date
    Mar 2004
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    15,801
    Quote Originally Posted by dejohan View Post
    when we would travel to those star formations, do we see those colors like that or not?
    Depends on what the image is trying to show. If it's natural colors, star colors and bright objects are probably about right, but cameras and eyes are different instruments. Faint objects like nebulae require long exposures the eye cannot perform. Very few astronomical images are shot to show what the human eye would see at a glance. Captions on the pictures, if you go to the point of origin anyway, will usually describe what you are looking at.

    The Bad Astronomer talks about Hubble processing and color in general, in What color is Mars (and take the side trip to the article about Hubble).

    Red giants are red.
    0 1 1 0 1 0 0 1 1 0 0 1 0 1 1 0 1 0 0 1 0 1 1 0 0 1 1 0 1 0 0 1 1 0 0 1 0 1 1 0 0 1 1 0 1 0 0 1 0 1 1 0 1 0 0 1 1 0 0 1 0 1 1 0 ...
    Skepticism enables us to distinguish fancy from fact, to test our speculations. --Carl Sagan

  3. #3
    Join Date
    Sep 2003
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    Adding to what 01101001 has said, the colors you see in the edited images are selected to enhance what scientists are observing. Our eyes will see most extended objects (non-point sources of light) as shades of grey.

    There are some exceptions, of course. Besides objects in our Solar system, which are brightly illuminated, by that very close star , there are a few nebulae that happened to be bright enough to reveal some color. The Eskimo nebula, for instance, has a very distinctive blue ring within it, but you need a large telescope to see this color with the naked eye.

    Blue stars are more bluish-white since all the other colors of the spectrum combine to dilute the strong blues. The color progression as we go to cooler and cooler stars is white, like our Sun, then yellow, then orange, then red. [I have yet to see one actually look red, but others seem to see some as red. I see them as orange.]
    We know time flies, we just can't see its wings.

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