How can you safely view the eclipse? Ask Science breaks down the misconceptions regarding eclipses glasses.
As the August 21st total solar eclipse quickly approaches, there has been an increased frenzy of reporting on how to view it safely. More than 12 million people live within the path of totality and, according to the Great American Eclipse, an estimated 2 to 7 million additional people will travel to the path of totality on eclipse day. The Great American Eclipse offers a map to illustrate where these visitors will be densest. 301 million Americans (that’s 92% of the population) further live within 700 miles of the path of totality or close enough to see the Sun obscured by at least 60%. That’s a lot of eyes on the eclipse.
Here is how to keep your eyes safe.
What if I just look for a few seconds?
It is never safe to look at the Sun directly without a filter.
Are eclipse glasses safe?
The American Optometric Association, the American Academy of Opthamology, the American Astronomical Society, and NASA have all clearly stated that viewing the eclipse through proper glasses or viewers is safe. So how do you know if your eclipse glasses (or handheld eclipse viewers) are the real deal? It used to be that looking for the ISO certification label was enough to know the glasses but with the high demand for the glasses, there have been reports of counterfeit pairs flooding the market with doctored or fake labels. The online retailer Amazon has added fuel to this fire by recalling many of their glasses with only a week to spare.
The American Astronomical Society has a list of approved, reputable vendors. You can test your glasses by checking that they filter out any light that is dimmer than the Sun. You shouldn’t see any ordinary household lights at all through proper eclipse glasses. Looking at the Sun through the glasses also should not be uncomfortable. If you ordered from Amazon but did not receive a recall notice from them, check your spam folder or contact them if you are still unsure. Even if they are from the approved list, make sure your glasses are not dented or scratched.
Can I wear regular sunglasses or a welder’s mask?
Regular sunglasses are not okay for solar eclipse viewing. (See the note above about not being able to see ordinary lights.) If you are opting for a welder’s mask, the American Astronomical Society recommends only a “Shade 14” filter or darker. Just as with the glasses, be sure the vendor that has labeled the shade is a reputable one.
When can I take the glasses off?
Unless you are in the 70-mile-wide path of totality, your eclipse glasses should remain on your eyes whenever you are looking up at the Sun. In all cases, remember to look down and away from the Sun before taking the glasses off. If you are in the path of totality, the window during which it is safe to remove the glasses is still a short one – between 2 and 2.5 minutes. Even near totality, keep your glasses on if you want to check out a Bailey’s bead.
What if I am not sure whether or not my glasses are safe?
If you are in doubt about your eclipse viewing tools, it is not worth the risk to your eyesight. Consider instead using a pinhole camera – they are easy to make with a few basic supplies and don’t involve staring up at the Sun at all. NASA has instructions posted on their website.
Check out my latest post/episode for more information on how to prepare for the solar eclipse on August 21st.