On Monday, August 21, a total solar eclipse will be visible across the entire United States. The totality will be observed in a narrow path from Oregon to North Carolina, affording millions of people the opportunity to see a memorable astronomical event. For those fortunate enough to witness this once-in-a-life-time event, caution is needed to avoid permanently damaging their vision.
From a young age, we’re told that staring at the sun is harmful. The lens inside your eye is more powerful than a typical hand-held magnifying glass. In effect, using a magnifying lens to burn a piece of paper would have the same result on the light sensitive photoreceptors of your retina. This is what happens when you look at the sun without proper protection.
There are safe ways to look at the sun and that is through special purpose solar filters. Ordinary sunglasses, even the dark ones, or homemade filters are not protective and should not be used for watching the solar eclipse.
You can view a solar eclipse using a pinhole camera (you can make one at home), solar viewing glasses, or a solar filter for cameras and binoculars. The American Academy of Ophthalmology (AAO) recommends that you carefully examine any solar filter for scratches or damage, as harmful rays can leak through and hurt your eyes. Once the moon completely covers the sun, you can safely view the eclipse without a filter for the very brief period of total eclipse. As soon as the sun starts to reappear, it’s important to continue viewing the event using the proper filter.
If you prefer to use solar viewing glasses, check your local library. NASA Library Initiative and the Moore Foundation are providing free glasses to libraries across the U.S. You can also purchase a pair at your local 7-Eleven, Lowe’s, Hobby Town, Toys R Us, and Walmart. Only four manufacturers have certified that their protective eye wear and solar viewers meet international safety standards. These companies are Rainbow Symphony, American Paper Optics, Thousand Oaks Optical and TSE 17. Do not use solar eclipse glasses to look through a camera, binoculars or a telescope, as the lenses of these optical devices can melt the filter and damage your eyes.