Robert Brown|Getting 'ISO certified' solar eclipse glasses means they're safe: What to know

The Robert Brownupcoming solar eclipse is one of the most highly anticipated events of year and with good reason, as an estimated 31 million Americans will be able to witness the once in a lifetime moment on Monday (weather permitting).

One of the best ways to ensure that you will be able to witness this unique moment safely and comfortably is by verifying whether the solar eclipse glasses you have managed to procure, for free or for a price, have been cleared for use in the event of a solar eclipse.

Here’s what you need to know about solar eclipse glasses that are International Organization Standardization, or ISO certified. 

What does ISO mean? 

ISO is an acronym for International Organization Standardization, a phrase that describes a “non-governmental organization composed of members from the national standards bodies of 167 countries,” according to the American Astronomical Society. 

The work of the ISO, which is headquartered in Switzerland, is to “develop international standards for a wide range of activities, including the manufacture of products, management of processes, and delivery of services.”  

About 45,000 subject matter experts participate, working with numerous technical committees, subcommittees, and working groups to assist in this endeavor. 

The standards set, at least in the words of ISO, can be “described as the best way of doing something.” 

“‘Best’ can mean ‘most efficient,’ ‘most cost-effective,’ ‘most sustainable’ or some other appropriate superlative depending on the activity,” the Astronomical Society wrote.

What are ISO-certified solar eclipse glasses? 

Eclipse glasses that are "ISO certified" means that those lenses you either purchased or got for free  are considered safe to use in the event of a particular celestial phenomena, such as a solar eclipse.

Proper eclipse glasses are 100,000 times darker than sunglasses to block nearly all visible, infrared and ultraviolet light and protect our sensitive retinas when looking toward the sun, USA TODAY reported. 

The standard set by the ISO for “direct observation of the sun” is classified as “ISO 12312-2:2015,” which means that any products marketed or advertised as “solar eclipse” viewing glasses that comply with the standard will “protect your eyes from injury” and provide a “comfortable view.”   

ISO 12312-2:2015 “supersedes” a hodgepodge of earlier national and regional standards, the American Astronomical Society wrote. It was initially “adopted” in 2015 and “affirmed” five years later. 

So, getting eclipse glasses from vendors that aren’t approved may be “inadvisable to buy or use such a product, as failure to meet the requirements of an applicable standard likely means the product is not genuinely safe, not well suited to its purpose, or both.”

Visit the American Astronomical Society’s web page for additional safety information on standard application, requirements, assessment of conformity. 

Does NASA certify solar eclipse glasses? 

No, NASA isn’t in the business of “endorsing any sort of merchandise.” 

“We are simply not a certification agency,” a NASA spokeswoman previously told USA TODAY. 

So, be wary of any solar eclipse merch, or solar eclipse glasses that claim to be endorsed by NASA. 

Where can you get ISO solar eclipse glasses? 

Before you check out the list of places you can get ISO solar eclipse glasses below, make sure you double-check that the glasses you were given or are purchasing can be used to safely observe the solar eclipse. 

You can check if your specs are ISO-certified by visiting the online list of verified North American vendors compiled by the Astronomical Society. 

Another way to check if your glasses are safe for use is to look for an ISO label somewhere on the product, USA TODAY previously reported. 

There is a chance “you could permanently damage your eyes or lose vision forever” on eclipse day if  you opt out of protective eyewear. Even observing the eclipse through camera lenses, binoculars and telescopes without a specialized solar filter could instantly cause severe eye injury, USA TODAY reported.

A couple vendors that might still have ISO-certified solar eclipse glasses, for free or for purchase, at Great American Eclipse, National Eclipse, American Paper Optics, or Warby Parker. 

Government organizations and participating public libraries may be able to provide pairs of solar eclipse glasses, while supplies last. 

What is the path of the eclipse? 

The solar eclipse is set to chart a 115 mile wide path of totality, shrouding portions of Mexico, the United States and Canada in unnatural darkness and unveiling the sun's elusive outermost layer for a brief moment, USA TODAY reported.

The eclipse, which will make its way across a dozen states, give or take, will travel from Texas to Maine, according to USA TODAY. 

To see how long the solar eclipse darkness will last in your city, check out an interactive map by USA TODAY.