So you’ve bought your solar eclipse glasses, and they have the right International Organization for Standardization number, also known as an ISO number.
But does that mean they’ll actually protect your eyes?
According to the American Astronomical Society (AAS), glasses should have a manufacturer label and ISO number 12312-2.
Some glasses are being sold with the proper ISO designation, but with lenses that, in reality, do not match the ISO number printed on them.
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While the only way to know for sure if glasses are legitimate is by buying them from a reputable vendor or testing them with lab equipment, there is a way for you to test if the glasses are fake.
According to the AAS, “you shouldn’t be able to see anything through a safe solar filter except the sun itself or something comparably bright.”
Some extremely bright lights – such as the exposed filament of an unfrosted incandescent light bulb or the reflection of the sun in a mirror-like surface may be visible – but household lights and lamps should not be.
According to the AAS, “[i]f you can see shaded lamps or other common household light fixtures (not bare bulbs) of more ordinary brightness through your eclipse glasses or hand-held viewer, and you’re not sure the product came from a reputable vendor, it’s no good. Safe solar filters produce a view of the sun that is comfortably bright (like the full moon), in focus, and surrounded by dark sky.”
When viewed through eclipse glasses, the sun should appear similar to a full moon. According to the AAS, if the sun appears uncomfortably bright, out of focus or surrounded by a haze, the glasses are fake.