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Would you see the stars in the day if blue were filtered?

  1. Jun 11, 2015 #1
    Would you be able to see stars in the day if the blue of the sky was filtered through an optical filter ? Can I make myself glasses using optical filters that'll enable me to look at the stars even in the day ? If the reason for the fact that we are unable to see stars in the day be the scattered blue light is brighter than the light of the stars , surely filtering out the blue light would enable me to see the stars even during the day .
     
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  3. Jun 11, 2015 #2

    phinds

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    A blue filter would allow you to see the other scattered wavelengths more clearly. Why do you suppose ground-based astronomers only go out at night?
     
  4. Jun 11, 2015 #3

    wabbit

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    Just one point, while it might possibly help, a filter is of limited use since the scattered light is not blue - if I am not mistaken it as a full spectrum, weighted towards the blue end but not limited to a small range of wavelengths, so you wouldn't be able to cleanly remove the scattered light.

    You can view some planets in daylight though (no need for a filter) but galaxies are far too faint and I doubt a filter would be of significant help. Also you do want to observe as much of the spectrum of the galaxy or star as you can.
     
    Last edited: Jun 11, 2015
  5. Jun 11, 2015 #4


    What if I filtered all the colours from violet to green ? Yes , you'd want to observe as much of the spectrum of the various stars as possible to make astronomical observations but for casual sky gazing , I think , filtering colours from violet to green won't make a huge difference .
     
  6. Jun 11, 2015 #5

    phinds

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    I'll ask you again, why do you suppose ground-based astronomers only go out at night?
     
  7. Jun 11, 2015 #6

    DaveC426913

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    I think the answer to this could have gone without saying but apparently not. The answer is because it's much better at night. Except that is not the OP's question.
     
  8. Jun 11, 2015 #7

    phinds

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    Fair enough.
     
  9. Jun 12, 2015 #8

    wabbit

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    It will make a big difference as you are attenuating the light from the stars too.
    Looking at https://en.wikipedia.org/wiki/File:Spectrum_of_blue_sky.svg from https://en.wikipedia.org/wiki/Diffuse_sky_radiation, the peak is above 500nm - it's more blue-tinted white that blue really.
    But the best thing to do I think is just try looking through some filters and see. You will need to protect your eyes from stray light though, so your pupils adapt to the lower intensity.
     
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