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How is it Possible to Look Near the Sun Without Getting Blinded?

  1. Aug 17, 2011 #1
    I've looked into optics and the biology of the eye, and I know that, although the fovea is an area with our highest visual acuity, light is still focused on the retina around the fovea even when we're not looking directly at something. Clearly it is not safe to look direct at the sun, but people often have the sun in their peripheral vision, even very close to their fovea, without losing their sight. My question is how.

    The cornea and lens are not so imperfect as to only focus light properly on the fovea, and if we can see the sun clearly in our peripheral vision, then the same intensity of focused light that would ordinarily be hitting the fovea if looking straight at the sun is still striking our retina. So why doesn't it burn our retina or at least cause us to lose our vision in that part of our eyes?

    Thanks.
     
  2. jcsd
  3. Aug 18, 2011 #2

    turbo

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    Gold Member

    The sun is very small, in terms of our field of view. You haven't defined what is "close" to the sun, so it is impossible to answer your question in terms of physiology. Looking at a scene and having the sun in your peripheral vision is not a a problem. You are looking around, and the movement of your eyes distributes the radiation from the sun over a wide range of your retina.

    I have incipient cataracts at ~59 years because when I was working ski patrol all winter through HS, I needed sunglasses to see, and none of them were designed to block UV. I would have been better off to wear NO sunglasses in the 60's because wearing sunglasses (even "good" ones, like B&L) allowed my pupils to widen in bright situations so that the UV could do even more damage.

    BTW, I never un-cap my telescopes during the day, when setting up for an evening of observation. I don't have any solar filters, anyway, and it would be devastating to have one of my nieces, nephews, etc blinded by "taking a peek" when I wasn't watching out for them.
     
  4. Aug 23, 2011 #3
    I remember back in elementary school when there was a solar eclipse we went outside but were told not to look at it directly. Confession: I looked. Several times. I was fine.

    Just a random story. Also, um, aren't teachers supposed to take courses in child psychology? I'm pretty sure the "Whatever you do, DON"T PUSH THE BUTTON approach" is really counterproductive, especially when you spend all day learning about the eclipse then go outside to look at it through mirrors with paper on them.
     
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