Around midday on Aug. 21, much of the nation will be looking to the skies as a total solar eclipse will be visible across a wide swath of the country. It’s a big deal because solar eclipses rarely cross the U.S. where they can be seen by the masses. Marketers have jumped onto the eclipse bandwagon with total abandon, selling everything from signs and banners to special glasses guaranteed to enhance your viewing experience.
But, sun-gazers, be warned: Some products may not provide enough protection for your eyes when looking directly at the eclipse.
In case you missed that day in science class, a solar eclipse occurs when the moon comes between the sun and earth, causing near-total darkness in a narrow “path of totality” and a dimming elsewhere, depending on your location. Here in central Mississippi, we will see a partial eclipse that day (weather permitting), and if you want to see the maximum effect, the closest viewing spots will be just to our north in middle and eastern Tennessee. But while we won’t witness “totality” here, it will still be spectacular, with the moon chomping nearly 90 percent of the sun for a few minutes. (For an animation of what we can expect to see, visit http://bit.ly/2flwWUW.)
Of course, your mom probably told you never to look directly into the sun, and it’s good advice as doing so can cause severe injury to your eyes. But many people think it’s OK to do so during an eclipse, as the sun is darkened. Actually, many people have suffered permanent eye damage as a result of trying to look at the partially darkened sun during an eclipse or using ordinary sunglasses, telescopes or binoculars.
NASA, medical associations, and others have warned that we need to be extra-careful when choosing how we’re going to look at the eclipse. “The only safe way to look directly at the uneclipsed or partially eclipsed sun is through special-purpose solar filters, such as “eclipse glasses” or hand-held solar viewers,” notes NASA in a post on its website. “Homemade filters or ordinary sunglasses, even very dark ones, are not safe for looking at the sun; they transmit thousands of times too much sunlight.”
Here are a few of NASA’s other tips for safe viewing:
Inspect your viewer. If your eclipse viewing device is more than a couple of years old, or if it’s scratched or damaged, don’t use it.
Avoid devices that concentrate the sun’s rays. Looking at the eclipse through a camera lens, binoculars, telescopes or other optical devices can be dangerous because they concentrate the sun’s rays onto a narrow point, potentially damaging your eyes.
Don’t assume your sunglasses will protect you. While most sunglasses do provide protection from UV rays in ordinary cases, they’re not designed to handle the brightness of looking directly at the sun. Check to see if your sunglasses are marked with the ISO 12312-2 certification. If not, get some that are.
Buy from reputable vendors. The American Astronomical Society has published a list of vendors selling products that provide adequate protection at https://eclipse.aas.org/resources/solar-filters.
Some welding glasses are OK, but not all. NASA suggests, if you have access to a welder’s glass with a No. 14 rating, it should be safe. But not all welding glass meets this standard, so if you’re not sure it’s No. 14 or better, don’t try it. “Do not view through any welding glass if you do not know or cannot discern its shade number,” NASA warns. “Be advised that arc welders typically use glass with a shade much less than the necessary #14. A welding glass that permits you to see the landscape is not safe.”
And if you can’t be outside during the eclipse, don’t worry; another total event will occur in 2024 to our north and west, and if you’re still around in 2045, mark your calendar for Aug. 12 of that year, when the path of totality will pass right over us in central Mississippi.