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Monday's letters: How to protect your eyes from the solar eclipse

Total eclipse | Aug. 10

Save your eyes

For the upcoming Aug. 21 solar eclipse, especially in Florida where the sun is blocked only partially (81.4 percent), it is important to wear ISO 12312-2 "solar eclipse glasses" if you look directly at the sun. This is because the pain nerve receptors in your eye have a higher pain threshold for light intensity than that for damage to your retina. Normally, if you look directly at the sun, it is too bright and hurts, and you look away quickly, This happens usually before the light can be focused onto the eye's retina long enough to do permanent damage. But if the sun's intensity is reduced to a lower level, say near 20 percent, there is not enough light intensity to trigger your pain threshold but there is still plenty of light intensity to cause permanent damage to the retina. Special ISA-12312-2 solar eclipse glasses reduce the light by 99.999 percent, and also reduce it in the UV and the infrared (which sunglasses usually do not). Also, do not use solar eclipse glasses in combination with a telescope or binoculars, because the large lens may collect say 10,000 times more light than your small pupil of your eye normally does, thus cancelling out the 99.999 percent reduction of the solar glasses.

The takeaway: Just because the reduced intensity of a partial solar eclipse does not cause you pain to look at the sun does not mean that you are not damaging your retina.

Finally, you can also view the image of the partial eclipse by using a pinhole projection box, or just by standing with your back to the sun, outstretching your two hands crossed, and using your slightly spaced fingers to form a waffle pattern. The shadow of your fingers on the ground will show the "pin hole" image of the sun caused by the small spaces between your fingers.

Dennis Killinger, Temple Terrace

The writer is Distinguished University Professor Emeritus in the Department of Physics at the University of South Florida.

Ticket request called a quota | Aug. 11

Officers can't do that

As a retired police officer with 30 years of service I speak from experience. The very thought of having to write two tickets per hour is ludicrous. The officer would have to be on the lookout for any minor infraction there is such as a broken taillight, no turn signal, etc. Instead of giving the motorist a warning officers would have write a ticket for any slight violations they observed. I couldn't bring myself to do that.

John Waitman, Palm Harbor

Trump escalates threats | Aug. 11

Seek a new deal

Kim Jong Un is not the only personification of the North Korean regime. The generals who advise him remember the ravages of a war 65 years ago for which no peace treaty was signed. Could it be that a comprehensive treaty, offered by President Donald Trump, would assuage North Korea's imagined threat from the United States and set the stage for new diplomatic negotiations? With a new relationship, both nations would be freed from the potential for an avoidable conflict.

Mike Rosenthal, Clearwater

Monday's letters: How to protect your eyes from the solar eclipse 08/11/17 [Last modified: Friday, August 11, 2017 5:32pm]
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