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The Doppler Effect on a still object?

  1. Feb 27, 2015 #1
    I noticed on my shadow that the left side had a blue outline, and the right side had a red out line, and it sparked my curiosity... It reminds me of the Doppler effect, because I came to notice that the side of the shadow that's furthest from me is always the red one, and the closer side is always blue. (To show what I'm talking about, I used some random picture of a shadow I found off google to demonstrate, https://dl.dropboxusercontent.com/u/229171533/Shadow%20Question.png [Broken].)

    Later, I noticed it's also with objects as well, and their outline too!

    So yeah, the point of this thread is, what's causing this?
     
    Last edited by a moderator: May 7, 2017
  2. jcsd
  3. Feb 27, 2015 #2

    Drakkith

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    That's a good question. I'm 99.99% certain it's not the doppler effect, but I don't know the actual reason.
     
  4. Feb 27, 2015 #3
    Yeah, I didn't really expect it to be the Doppler effect, but I can't think of what else it would be.
     
  5. Feb 28, 2015 #4
    Do you wear glasses? I bet it is chromatic aberration. Even your unaided eyes suffer from chromatic aberration, but glasses generally make it much worse. Especially if you have high index glasses and/or a high prescription.
     
  6. Feb 28, 2015 #5
    Well, I got that picture that I used to demonstrate (https://dl.dropboxusercontent.com/u/229171533/Shadow%20Question.png [Broken]) right off the internet... And I've tested that with multiple pictures of shadows I've found around google images before coming here... That being said, yes, I do wear glasses, but the fact that it shows up in those pictures still must mean something.... Right? Those aren't my eyes taking the pictures...
     
    Last edited by a moderator: May 7, 2017
  7. Feb 28, 2015 #6
    Yeah, cameras also suffer from chromatic aberration. The error should be small for a quality compound lens, but maybe not so good on a cell phone camera or a low quality lens.
     
  8. Feb 28, 2015 #7
    I'd check without my glasses, but you said my unaided eyes will do the same thing.... If you don't wear glasses, can you make a dark shadow somehow and observe the left and right borders of it really carefully and tell me what you see?
     
  9. Feb 28, 2015 #8
    A mix of diffraction and refraction, I suppose.
    Shadow edges are not as sharp as one would think, but are a bit fuzzy due to edge diffraction.
    The temperature of the air close to your body, and for most objects in sunlight, would be at a different temperature than the surrounding air causing a refraction effect.
    Perhaps the two put together can explain the colors that you see. ??

    See this 'stunningly' spectacular effect with a shadow.
    http://www.usaukonline.com/latest-news/3704-ghosts-of-the-mountains-natural-light-phenomenon-leaves-haunting-halo-around-shadow.html [Broken]
     
    Last edited by a moderator: May 7, 2017
  10. Feb 28, 2015 #9

    jtbell

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    In the photograph, it's almost certainly chromatic aberration. I see it in my pictures from all my cameras over the years, most noticeably near the edges of the image.

    I'm very nearsighted, so I have to wear eyeglasses with a very strong prescription. About thirty years ago, I had eyeglasses with a then-new kind of high-index glass that allowed the lenses to be about half as thick at the edges, as before. They also had a lot of chromatic aberration. I could look at the gas discharge tubes that we used in our spectroscopy labs, out of the corner of my eye, and see a very nice spectrum. :woot:

    Fortunately, optical technology has improved since then. My current eyeglasses have much less chromatic aberration, even though they're even thinner than those eyeglasses. However, I can still see colored fringes if I look carefully.
     
  11. Feb 28, 2015 #10
    I feel like this contradicts general relativity but the earth is in constant motion. The difference between blue and red light is just nanometers. The earth's motion could cause the smallest shift, since light has no mass, therefore cannot be apart of the inertial motion of the earth. Hope this helped.
     
  12. Feb 28, 2015 #11

    A.T.

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    Search images for "chromatic aberration", and you will find even more pictures of it. You will notice that it has nothing to do with shadows, but also becomes visible at other high contrast boundaries. Image editing software even has filters to remove this very common effect.
     
    Last edited by a moderator: May 7, 2017
  13. Feb 28, 2015 #12
    So the answer is chromatic aberration... That's interesting. It's nice to finally have an answer for this, I've been wondering where the lines were coming from forever. Thanks you guys!
     
  14. Mar 1, 2015 #13

    davenn

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    I spend lots and lots of money on very expensive camera lenses that have the chromatic aberration kept to an absolute minimum :smile:
     
  15. Mar 1, 2015 #14

    Drakkith

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    Uh, no, this has absolutely nothing to do with it.
     
  16. Mar 1, 2015 #15
    Hey guys,
    According to me its not much of chromatic aberration.its the same thing as dispersion of light becoz of a prism.it has differnt refractive indices for different wavelenghts of light thats the thing which seperates lights into its components.just replace the prism with air.
     
  17. Mar 1, 2015 #16

    Drakkith

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    The air is not acting as a prism here. It's most likely chromatic aberration by the camera/glasses lens. (chromatic aberration is just the uncorrected dispersion of light by a lens)
     
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