AILSA CHANG, HOST:
The big day is finally here. In mere hours, folks in 14 states will get to see a total solar eclipse. It's the first one visible from coast to coast in the U.S. in nearly a hundred years. The rest of the country will enjoy a partial solar eclipse. And NPR's Nell Greenfieldboyce has this important reminder about safety.
NELL GREENFIELDBOYCE, BYLINE: Ralph Chou has seen 18 total solar eclipses. He's also an optometrist and vision scientist at the University of Waterloo in Canada. And he says pretty much every time there's a solar eclipse, somebody gets hurt.
RALPH CHOU: The ones we're really concerned about are the people who have never seen an eclipse before or, you know, just decided that, you know, today's a nice day to go take a look at a solar eclipse. And, oh, I probably don't need to do very much to get ready to do that. Then I get worried.
GREENFIELDBOYCE: He says you really can get blurred vision or blind spots after watching partial eclipses without protection, even if there's just a little crescent of sun left in the sky.
CHOU: I've seen a couple of patients over the years where, you know, you've got very distinct crescent-shaped scars from looking at a solar eclipse, where you can almost tell when they looked.
GREENFIELDBOYCE: So it is never safe to look at a partial eclipse without special eclipse glasses or filters. And most of the country will only see a partial eclipse. Chou says the risk of eye injury is even greater if you look at a partial eclipse unprotected through a telescope or binoculars or a camera lens.
CHOU: The damage can happen extremely quickly.
GREENFIELDBOYCE: It is also not safe to look through binoculars or telescopes while just wearing regular old eclipse glasses. Those devices need specialized filters. But it is all right to put eclipse glasses over your everyday prescription eyewear. Chou says in past eclipses, it's younger people who seem more likely to ignore safety warnings.
CHOU: It does tend to be young males - teens to early 20s - the ones who don't think about any protection for a number of different circumstances.
GREENFIELDBOYCE: So, parents, warn your kids. Now, if you're lucky enough to be in the thin stretch of land across the country that's going to see a total solar eclipse, it's OK to look with your naked eyes during totality, the couple of minutes or so when the moon is completely covering the sun. In fact, it's more than OK.
RICK FIENBERG: It is spectacularly beautiful. And there's nothing else like it. It's kind of like falling in love. I mean, you can't describe what that is unless you've experienced it.
GREENFIELDBOYCE: Rick Fienberg is with the American Astronomical Society. He's seen a dozen total solar eclipses so far.
FIENBERG: Going through life without seeing a total eclipse of the sun would be like going through life without ever falling in love. It would be a terrible shame not to have that fundamental, wonderful experience.
GREENFIELDBOYCE: When the sun completely blinks out, take those safety glasses off. But the instant a sliver of light returns, put those glasses back on. Nell Greenfieldboyce, NPR News.
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