On August 21st the U.S. will experience a rare phenomenon, a nationwide solar eclipse. Because this upcoming one can be seen from the east coast all the way to the west, millions of Americans will view it.

Obviously you cannot stare directly into the sun, even during an eclipse, without doing permanent damage to your eyes. Special sunglasses with solar filters are required. These glasses, covered in an opaque polymer film embedded with carbon powder, are so dark that they admit no light at all unless you're staring into the sun; everything else is pitch black. And despite the fancy material, these glasses aren't expensive, with prices ranging from 99 cents (with paper frames) to $30 (plastic frames).

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Unfortunately, as Reuters reports, the market has become flooded with manufacturers selling fakes.

"It's a bunch of unscrupulous people cashing in on the eclipse and putting public safety at risk," said Richard Fienberg, press officer for the American Astronomical Society (AAS).

Staring at the sun without proper filtration, even when it is partially obscured by the moon during an eclipse, can damage or destroy photo-receptor cells of the eye's retina, leaving blind spots in a person's field of vision, experts said.

To combat this, the AAS has put together a list of brands and suppliers that they know are legit. "If a supplier isn't listed here, that doesn't mean its products are unsafe — only that we have no knowledge of them or that we haven't convinced ourselves they are safe," the AAS writes.

"Eclipse Glasses" & Handheld Viewers

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Solar Viewer Brands

American Paper Optics (Eclipser) / EclipseGlasses.com / 3dglassesonline.com

APM Telescopes (Sunfilter Glasses)*

Baader Planetarium (AstroSolar Silver/Gold Film)* [see note]

Celestron (EclipSmart Glasses & Viewers)

DayStar (Solar Glasses)

Explore Scientific (Solar Eclipse Sun Catcher Glasses)

Lunt Solar Systems (SUNsafe SUNglasses) [see their unique kid-size eclipse glasses]

Meade Instruments (EclipseView Glasses & Viewers)

Rainbow Symphony (Eclipse Shades)

Seymour Solar (Helios Glasses)

Thousand Oaks Optical (Silver-Black Polymer & SolarLite)

TSE 17 (Solar Filter Foil)*

*Based outside the United States.

Astronomy, Science & Optics Vendors

Adorama Camera

Agena AstroProducts

Alpine Astronomical

AmericanEclipseUSA.com

American Science & Surplus

AstroBox/EclipseKit.com

Astronomers Without Borders

Astronomical Society of the Pacific

Astronomy Magazine / My Science Shop

Astroshop.eu

Astrozap Telescopes & Accessories

B&H Photo Video

Charlie Bates Solar Astronomy Project

Company Seven

David Chandler Company

Discover Magazine / My Science Shop

EarthSky.org

Eclipse2017.org

Eclipse for a Cause

EclipseGlasses.co.uk

EclipseStuff.com

Explore One

Flinn Scientific

GreatAmericanEclipse.com

High Point Scientific

Khan Scope Centre

Land Sea & Sky

Lire la Nature & Astronomie Plus

MMI Corporation

NationalEclipse.com

Oceanside Photo & Telescope

Online Science Mall

Ontario Telescope & Accessories

Optics Planet

Orange County Telescope

Orion Telescopes & Binoculars

Science City at Union Station

Sky & Telescope Magazine / Shop at Sky

SkyNews Magazine

Space Racers / AugustEclipse.com

Space Update

Starizona

Steve Spangler Science

The Planetary Society

Woodland Hills Camera & Telescopes

Retail Chains Where You Can Buy In-Store Only (Not on Their Websites)

7-Eleven

Best Buy

Bi-Mart

Casey's General Store

Circle K

Hobby Town

Kirklands

Kroger

London Drugs

Love's Travel Stops

Lowe's

McDonald's (Oregon only)

Pilot/Flying J

REI (Recreational Equipment, Inc.)

Toys "R" Us

Walmart

Online & Other Vendors

123 Sales

2017Solar.com

3Dstereo.com

Educational Innovations

Electronic Analyst

Firefly Buys (FFB)

Fred Meyer

Freedom Hill

Mega-Fun Toys

Off the Wall Toys & Gifts

Run to Shop

Skyhawk Ventures

Solar Eclipse Spectacles (paper glasses only)

Soluna/GSM Sales

Squirrellynuts

ThinkGeek

Your 5 Star General Store

Free

The AAS also reports that NASA, Astronomers Without Borders and some libraries are giving away safe solar eclipse glasses for free. Click here and scroll down for details.

Our thanks to AAS for taking the time to put this list together!