There is no physical relationship between a total solar eclipse and your health, any more than there is a relationship between your health and a new moon,” NASA says. Physically, the only concern should be your eyes. You won’t go blind from looking at the eclipse, but it can cause retinal damage so make sure you’re wearing protective eye glasses but it’s important to make sure they’re of the right quality. Don’t use sunglasses, smoked glass, an unfiltered telescope and magnifiers or polarized filters as a way to view the eclipse.
The only glasses that should be used to look at a partially eclipsed sun is with eclipse glasses that meet an international standard, ISO 12312-2, according to the American Optometric Association.
That international safety standard, which is set by the International Organization for Standardization, means the glasses reduce visible sunlight to a safe level, and block ultraviolet and infrared radiation, according to the American Astronomical Society website. According to the ISO, the safety standard is reviewed every five years.
Blocking that radiation is important. Ultraviolet, or UV, radiation can damage the cells of the eyes, while the infrared, or IR, radiation can generate heat that causes thermal damage, according to the National Eye Institute.
How to make sure the eclipse glasses you bought are real: Real eclipse glasses will have a note about the international standard somewhere on their body, according to the American Astronomical Society. Before buying, make sure the glasses are advertised as meeting this standard.
If you already bought the glasses, check the arm for the the “ISO 12312-2” label. The standard may also be written as “ISO 12312-2:2015,” the AAS says on its website. Either designation means that the glasses will block light and radiation.
The label may be on the flat or curved part of the arm.
NASA has also released guidance on how to test your eclipse glasses. The space agency recommends putting on your glasses and finding a bright light. If the light appears extremely dim, or doesn’t appear at all, when you look at it through the glasses, they are legitimate. You should only be able to see the filament of the bulb, not its glow.
How to avoid buying fake solar eclipse glasses: Checking for the international standard isn’t foolproof: It’s possible for sellers with products who do not meet the standard to label their eyewear with it anyway. To avoid this, make sure you’re ordering glasses from a reliable source.
The American Astronomical Society advises against ordering from Amazon, Temu or other online marketplaces, and recommends against ordering if prices seem to be too good to be true. The AAS also said it’s best to purchase from manufacturers based in the United States. Counterfeit glasses have been sold by companies based overseas.
The organization maintains a list of reputable vendors of solar eclipse glasses.
The ISO, the body that established the international standard for eclipse glasses, also sells them on its website.
Why it’s important to double-check older solar eclipse glasses: If you’re reusing glasses from a previous solar eclipse, it’s important to double-check that they are still in good condition. NASA warns against using glasses that have any marks or scratches on them. This damage can diminish the protection they offer. Glasses that have punctured lenses should also not be used.
Glasses that are more than three years old should not be used to view the 2024 total solar eclipse, according to the National Eye Institute — so if you saved your glasses from the 2017 eclipse, you may want to think about finding a new pair.
What happens if you don’t have eclipse glasses? NASA says if you don’t have eclipse glasses or a handheld solar viewer, you can use an indirect viewing method like creating a pinhole projector or eclipse projector. The indirect methods do not involve looking at the Sun.
How to make sure your homemade eclipse viewing tool is safe: NASA recommends making a pinhole projector, which uses a small opening like a hole punched in an index card, to project an image of the sun onto a nearby surface. When using a pinhole projector, keep the sun at your back and view the projected image to safely see the eclipse. However, to do this safely, it’s important to make sure to avoid actually looking at the sun itself.
And finally: Can I look at the eclipse through my phone? Once you have your glasses on properly, you can look at the eclipse. And, look away from the sun before taking your glasses off. Do not look at the eclipse through a camera or phone lens, telescope, binoculars, or any other optical device.
Hope this is helpful, have fun on this historic day and stay safe.