Solar viewers (also known as solar viewing glasses or solar eclipse glasses) are special

eyewear Eyewear is a term used to refer to all devices worn over both of a person's eyes, or occasionally a single eye, for one or more of a variety of purposes. Though historically used for vision improvement and correction, eyewear has also evolved into ...

designed for direct viewing of the

Sun The Sun is the star at the centre of the Solar System. It is a massive, nearly perfect sphere of hot plasma, heated to incandescence by nuclear fusion reactions in its core, radiating the energy from its surface mainly as visible light a ...

. Standard

sunglasses Sunglasses or sun glasses (informally called shades or sunnies; more names Sunglasses#Other names, below) are a form of Eye protection, protective eyewear designed primarily to prevent bright sunlight and high-energy visible light from damagin ...

are unable to filter out eye-damaging radiation. Solar viewers can be used for safe viewing of solar events such as

eclipses An eclipse is an astronomical event which occurs when an astronomical object or spacecraft is temporarily obscured, by passing into the shadow of another body or by having another body pass between it and the viewer. This alignment of three ...

. The recommended

optical density Absorbance is defined as "the logarithm of the ratio of incident to transmitted radiant power through a sample (excluding the effects on cell walls)". Alternatively, for samples which scatter light, absorbance may be defined as "the negative log ...

of this eyewear is 5, meaning that the solar viewing filter only permits 1 part in 100,000 of incident light to pass through. In addition to blocking visible light, solar viewers also block

ultraviolet Ultraviolet radiation, also known as simply UV, is electromagnetic radiation of wavelengths of 10–400 nanometers, shorter than that of visible light, but longer than X-rays. UV radiation is present in sunlight and constitutes about 10% of ...

and

infrared Infrared (IR; sometimes called infrared light) is electromagnetic radiation (EMR) with wavelengths longer than that of visible light but shorter than microwaves. The infrared spectral band begins with the waves that are just longer than those ...

rays which can damage one's eyes.

Safety

According to the

American Astronomical Society The American Astronomical Society (AAS, sometimes spoken as "double-A-S") is an American society of professional astronomers and other interested individuals, headquartered in Washington, DC. The primary objective of the AAS is to promote the adv ...

(AAS), products meeting the

ISO The International Organization for Standardization (ISO ; ; ) is an independent, non-governmental, international standard development organization composed of representatives from the national standards organizations of member countries. Me ...

12312-2 standard are safe for direct solar viewing. The AAS maintains web pages giving detailed information about safe solar viewers and a list of reputable vendors of eclipse glasses. The organization warned against products claiming ISO certification, or even citing the exact standard number, but not tested by an accredited laboratory, or those bearing incomplete certification information. Another problem was counterfeits of reputable vendors' products, some even claiming the company's name (such as with American Paper Optics, which published information detailing the differences between its glasses and counterfeits). Solar viewers manufactured prior to 2015 may have a three-year limit before they can no longer effectively filter out UV radiation and should no longer be used. Starting in 2015, products manufactured to meet the standards of ISO 12312-2 can be used indefinitely as long as they have not been damaged by scratches or tears. Solar viewers should be used for safe viewing of the Sun during partial solar eclipses and during the partial phases of a total solar eclipse event, when the Moon only covers a portion of the Sun's surface. Only during the brief period of totality of a total solar eclipse is it safe to view the Sun directly with the naked eye.

Counterfeit eclipse glasses

In the months leading to the

solar eclipse of August 21, 2017 The solar eclipse of August 21, 2017, dubbed the "Great American Eclipse" by some media, was a total solar eclipse visible within a band that spanned the contiguous United States from the Pacific Ocean, Pacific to the Atlantic Ocean, Atlantic c ...

, counterfeits of light-filtering glasses for solar eclipses began proliferating. Effective eclipse glasses filter visible, ultraviolet, ''and'' infrared light. The eye's retina lacks pain receptors, and thus damage could occur without one's awareness. Includes photos of genuine and fake eclipse glasses. The AAS said determining whether an eclipse viewer was safe required a spectrophotometer and lab equipment, but often the user should see nothing through the filter except for the Sun, sunlight reflecting off shiny metal, or intense light sources such as an LED flashlight. Andrew Lund, the owner of a vendor of eclipse glasses, noted that not all counterfeit glasses were necessarily unsafe. He stated to ''

Quartz Quartz is a hard, crystalline mineral composed of silica (silicon dioxide). The Atom, atoms are linked in a continuous framework of SiO4 silicon–oxygen Tetrahedral molecular geometry, tetrahedra, with each oxygen being shared between two tet ...

'' that the counterfeits he tested blocked the majority of harmful light, concluding that "the IP is getting ripped off, but the good news is there are no long-term harmful effects." On July 27, 2017, Amazon required all eclipse viewing products sold on its website have a submission of origin and safety information, and proof of an accredited ISO certification. In mid-August 2017, Amazon recalled and pulled listings for eclipse viewing glasses that "may not comply with industry standards", and gave refunds to customers who had purchased them. On April 8, 2024, the

Illinois Department of Public Health The Illinois Department of Public Health (IDPH) is the code department of the Illinois state government that prevents and controls disease and injury, regulates medical practitioners, and promotes sanitation. IDPH offices The Illinois Department ...

issued a recall on specific brands of eclipse glasses that failed to meet proper safety standards.

References

{{Eyewear Eyewear Ophthalmology Prevention Fashion accessories Solar viewing glasses 2010s fashion Solar eclipse articles

Safety

Counterfeit eclipse glasses

See also

References