Shining Light - The Physics Behind This Phenomenon?

  1. I've taken a picture of my christmas lights. I'm wondering if someone could help me explain, or at least name, the phenomenon?


    Why does light appear to come from 4 distinct points around the light? Even though some bulbs are rotated, the position of these 4 points do not rotate with it. It's always -up-, -right-, -left-, and -down-. Why?

    If someone could link me to an article about this phenomenon, or at least give me a name of it, that would help a lot. Some of my friends are saying it has to do with spherical aberration. But I don't understand how. It seems, to me, to be spherical aberration and the following pattern at the same time:


    Which could be caused by refraction, right? But how?

    Thanks for any replies.
    - Sane
  2. jcsd
  3. what happens when you rotate the camera?

    It could be diffraction or saturation of the detector array.
  4. It's always up with respect to the orientation of the camera. I took another picture to clarify:

    So I guess that means it has to do with the lens inside the camera. Is there anything specific I can research?
  5. russ_watters

    Staff: Mentor

  6. Diffraction spikes, brilliant! Thanks. I get many excellent hits with this term.

  7. Do eyelashes cause a similar phenomenon? How about the iris of a camera?
  8. It seems like it'll be anything that obstructs light directly before entering the lens. You can even place strings in front of a telescope and get diffraction spikes (as russ_watters has apparently done).
  9. I could not find an objective explanation of Diffraction Spikes anywhere... not even on Wikipedia. Most sites just referenced little things you could do, and the overall effect. I found a couple sites that explained very briefly what happens, so I tried to piece together all of these things to make the following analysis of my photo.

    (Disclaimer: This may not be 100% accurate, but if it helps anyone else who stumbles upon this thread get a better understanding of Diffraction Spikes, then great. And maybe someone could help correct any inaccuracies/elaborate on my analysis.)

  10. i don't understand how a solid object can bend light... i thought you need strong gravity to do that, as in huge stars in space? Shouldn't you just get a shadow star or something...
  11. That's one thing I wasn't clear on myself, and need to explain better once I understand it more. I don't think it's so much that it's bending it, but that the waves can go around obstacles. And that results in interference. Similar to the Double Slit Experiment. I think... Clarification, anyone?
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