Regular sunglasses or squinting to see it might leave you with burns. No matter what part of the country you're watching from, here's how to see this awe-inspiring astronomical event safely.

August 09, 2017

It's rare, spectacular, and almost here: on August 21, a total solar eclipse will be visible across the United States, in a 70-mile-wide swath that stretches from Oregon to South Carolina. For a stunning two minutes, the moon will completely cover the sun. Those in the “path of totality,” as this swath is called, will experience night-like darkness in the middle of the day.

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For everyone else, a partial eclipse will be visible throughout North America, during which daytime skies will darken somewhat. But whether you live in the path of totality or will only witness the partial eclipse, to view the event, you need to put on special eyewear and take other precautions—or you risk damaging your sight. (The exception is during those two minutes of total darkness in the path of totality, as the sun is completely covered by the moon and it can't harm you.) 

Here’s what you need to know about protecting your peepers to witness this astronomical phenomenom.

Blinded by the light

You wouldn't stare at the sun in the middle of a regular day for the same reason you shouldn't glance at it during an eclipse. “It’s almost impossible to have a sense of how powerful the sun’s rays are when they are focused,” says Russell N. Van Gelder, MD, PhD, professor of ophthalmology at University of Washington School of Medicine and past president and clinical spokesperson for the American Academy of Ophthalmology.

To get an idea, remember how as a kid, you may have used a magnifying glass on a sunny day to burn leaves? This is what will happen to your peepers: Your retina will literally be burned by the sun, a phenomenon called “solar retinopathy.”

Looking at a partial eclipse carries the same risk. “The concentration of photons is the same even when you are looking at a sliver of the sun. The only difference is you would have a smaller amount of damage because it would affect less of your retina,” explains Dr. Van Gelder.

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There is currently no known treatment for solar retinopathy, and the damage may be permanent. “If you lose retina tissue, it’s gone forever,” says Dr. Van Gelder. “The risk is that you will irreversibly damage your eye and end up with a blind spot.” The best treatment is prevention, but if you do experience vision problems after the eclipse, be sure to visit an ophthalmologist as soon as possible. 

The protective eyewear you need

Don’t even think about trying to view the eclipse through a pair of regular UV-blocking sunglasses or welders’ glasses; these offer zero defense, says Dr. Van Gelder. You will need approved “eclipse glasses,” which are not just souped-up sunglasses, he points out.

While they resemble old-fashioned, flimsy 3-D glasses, eclipse glasses are actually powerful light blockers. Try on a pair, and you’ll notice that they turn the room pitch dark, as though you are wearing a blindfold. If you wear them outside before the eclipse, the only thing you’ll be able to see is the sun.

Anyone can try to make a buck off the event by selling dark shades and calling them eclipse glasses. So it’s important to ensure that the glasses you buy are stamped “ISO 12312-2” and are also on this “approved vendor” list compiled by the American Astronomical Society.

If you accidentally purchase a counterfeit pair, you will know right away, says Michael Kirk, PhD, a research scientist in the heliophysics science division at NASA’s Goddard Space Flight Center with Catholic University of America. “Your eyes are pretty smart; if you are looking at the eclipse and it’s uncomfortable or you are squinting, then you don’t have the proper eye wear, and you should look away,” he says.

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Special caution for kids

Planning to watch the eclipse with children under six? Kirk suggests having them view the eclipse another way, such as through a pinhole viewer or by watching the shadows on the ground. “There’s too much risk that the glasses might slip or fall off, or that kids might take them off,” he says, and end up burning their eyes.

If your kids are too young to enjoy the eclipse today, they'll have another chance during the next total solar eclipse on April 8, 2024, which will arc from Texas to Maine. “We’ll have these two total eclipses back-to-back,” Kirk notes, followed by a long eclipse absence again.