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B Is it possible to see sunspots with the unaided eye?

  1. Aug 24, 2017 #1
    This has been bugging me for a while, I'm not sure what I saw exactly. A few months ago there was some thin clouds blowing past the sun, obscuring it to the point you could easily look at the disk with the unaided eye. There was a dark spot, that looked like a sunspot as seen in filtered pictures of the sun. The clouds were blowing by fast and the spot didn't change position on the sun for 10-15 minutes I was watching it. Is a sunspot a rational explanation for it?
     
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  3. Aug 24, 2017 #2

    phinds

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  4. Aug 24, 2017 #3

    russ_watters

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    Yes, but they have to be ginormous.
     
  5. Aug 24, 2017 #4

    fresh_42

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    Unlikely. More likely is that you already damaged your retina, which produces the dark point. I strongly recommend NOT to look into the sun with unprotected eyes, and sunglasses are NOT sufficient, clouds even less. This is a sure way to burn your retina or parts of it with no chances to ever get recovered. DO NOT DO THIS!
     
  6. Aug 24, 2017 #5
    I would think the dark point would move around with my vision (like floaters, which I have). Not stay exactly the same place on the sun for 10-15 minutes

    Edit: I was not staring at it the whole time, I kept looking back at it when it wasn't too bright. But wise advice nonetheless
     
  7. Aug 24, 2017 #6

    Bandersnatch

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    Do you know the exact date it happened?
     
  8. Aug 24, 2017 #7
    No, unfortunately not.
     
  9. Aug 24, 2017 #8

    Andy Resnick

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    Yes, sunspots have been viewed with unaided eyes for millennia:

    https://www.windows2universe.org/sun/activity/sunspot_history.html
    http://chandra.harvard.edu/edu/formal/icecore/The_Historical_Sunspot_Record.pdf
     
  10. Aug 24, 2017 #9

    OmCheeto

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    According to Stavros you can:

    A fun experiment I just devised, to see if you can see sunspots with your naked eye:

    1. Pull up Stavros's image of the sunspots on your computer.

    2017.08.24.OmCheeto.eyeball.resolution.png

    2. Aim it towards a distant location.
    3. Measure the diameter of the sun on your monitor.
    4. Walk as far away from your monitor as possible.
    5. Start walking towards your monitor, until you can just "sense" that the sunspots are present.
    6. Measure the distance to your monitor.
    7. Do a bunch of fancy maths, and determine the angular resolution of your eyes. [3]
    8. Google the angular diameter of the sun as viewed from Earth. [1]
    9. If the angular resolution of your eyes[2] is greater than the angular diameter of the sun, then you cannot see sunspots.

    ps. I cannot see sunspots with my naked eyes. Though, I'm old, and accept the fact that all of my equipment is wearing out, and am not ashamed to admit it.

    [1] 32 arc-minutes (sun as seen from earth)
    [2] 100 arc-minutes (Om has to magnify the sun 3 times to see sunspots.)
    [3] I would do this for you, but I did the maths long ago in the "Ceres" thread, where I plugged the equations into a spreadsheet, as I knew it would come in handy one day, as I can't remember my sines from cosines for squat. But, I'm sure it wasn't that hard.
     
  11. Aug 24, 2017 #10
    The one I saw back on July 13 was huge. But still I was wearing solar eclipse glasses (no magnification due to other instruments).
    With totally naked and unaided eye it's a bad idea! @fresh_42 's warning is an important one!

    Subsequent sun spots have been much smaller and I haven't been able to see them with just the solar glasses - I admit it too.
    The latest ones (around eclipse time) are just about visible with binoculars (I used 12×30 even today) [&filter], if you focus properly and you know where to look ...
     
  12. Aug 24, 2017 #11

    davenn

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    yes a good explanation


    I agree with Russ .... yes but they have to be pretty large ones


    That is unfortunate as I have a full set of data that goes back many years

    you cant even give a month and part of that month .... I don't need the specific day


    that is true ... sunspot is most likely reason

    Dave
     
  13. Aug 24, 2017 #12
    Thanks everyone for the comprehensive answers
     
  14. Aug 24, 2017 #13

    davenn

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    you didn't answer my Q
     
  15. Aug 24, 2017 #14
    Sorry it was so long ago, thinking more about it I think it was 2.5 years ago (from my memory of where I was working) best guess is February-March 2015 or earlier. That's the best I can come up with
     
  16. Aug 24, 2017 #15

    davenn

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    ohhh ok ... in your OP you said a few months ago, hence why I questioned you :wink:
     
  17. Aug 24, 2017 #16
    It was something I didn't think much about at the time, the eclipse (which btw was amazing) made me think about it again.
     
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