Why You Really Do Need Eclipse Glasses—and Why You Should Buy Them Right Now

Elana Spivack
·2 min read
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This is One Thing, a column with tips on how to live.

Few natural phenomena bring sci-fi-esque buzz like a solar eclipse. Some people talk about this astronomical event as if it comes straight out of a Ray Bradbury story. And those people are right! Solar eclipses are, without hyperbole, awesome. And just in case you haven’t heard, there’s one happening on April 8.

Of course, a cardinal rule of day-to-day life still applies to eclipses: You must absolutely not look at the sun directly—even if it’s partially obscured by the moon. It can cause permanent retinal damage.

Photoreceptors in the eyes register and convert light to electrical signals detected in your brain. The powerfully incandescent sun overwhelms those photoreceptors, bombarding them with far more light than they can convert. Any light your photoreceptors don’t absorb filters through to the back of your eye, producing heat. Although the moon partially blots out the sun, that doesn’t make the rays that are visible any less potent. Look at a partial eclipse long enough and you can burn the sun into your retinas, which can result in a permanent hole in your vision called a scotoma. Since your retinas lack pain receptors, you won’t know that the damage has been done until it’s too late. Looking through conventional binoculars or telescopes doesn’t mitigate this risk.

That’s why it’s imperative to procure special viewing glasses fitted with solar filters. The black polymer lenses are made of a flexible resin filled with carbon particles. Blocking nearly all visible light, and 100,000 times darker than typical sunglasses, these filters will protect your peepers. Safe eclipse glasses come with a certified label ISO 12312-2, which stands for International Organization of Standardization. These products have been verified compliant with modern standards for beholding eclipses.

These glasses are not expensive—you can find them for about $10 for 5. (Price gougers, however, may try to persuade you to pay upward of $10 or even $20 for a single pair of these flimsy-yet-essential frames.) But they sold out many places ahead of the 2017 eclipse. I myself was stuck looking at a shadow of the moon partially blocking the sun through a pinhole poked in tinfoil and fitted in a cereal box, one of the DIY workarounds that allow you to view the solar eclipse indirectly without hurting your eyes. (There’s also a trick that involves a colander.)

It was cool, but not nearly as cool—I would imagine!—as looking at the main event. So go buy a few pairs of glasses right now. You can find a full list of websites selling approved solar eclipse glasses here. Or, if you can dig up your eclipse glasses from 2017 and they are intact, they will still work, according to the American Academy of Ophthalmology. Happy viewing!