Eclipse viewing glasses: How to protect your eyes during a total solar eclipse

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Students wear goggles to view the partial solar eclipse over Schiedam, Netherlands, in June 2021.

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There will be a stunning total solar eclipse Visible to millions of people across Mexico, the United States and Canada On April 8th.

Astronomers encourage everyone to enjoy this rare view one last time until August 2044, but only if they can do so safely. Sunglasses will not be enough to protect your eyes at this celestial event.

a Total solar eclipse It occurs when the moon passes between the Earth and the sun, completely blocking the face of the sun.

Those located in the path of totality, or locations where the Moon's shadow will completely cover the Sun, will witness a total solar eclipse. People outside the path of totality will still be able to see a partial solar eclipse, in which the Moon obscures only part of the Sun's face.

If your location only offers a partial solar eclipse view, some strong sunlight will always be visible. Any glimpse of the sun's brightness with the naked eye is not only uncomfortable, it is dangerous.

The only time when it is safe to see the sun without eye protection is during a “total eclipse” of the sun, or the brief moments in which the moon completely blocks the sun's light, according to the American “space” website. NASA.

Staring directly into the sun can lead to blindness or double vision. During the 2017 total solar eclipse, it was a young woman Diagnosis of solar retinopathyDamage to the retina as a result of exposure to solar radiation, in both eyes after viewing the eclipse with what doctors believe to be eclipse glasses that do not adhere to safety standards.

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There is no cure for solar retinopathy. It can get better or worse, but it is a permanent condition.

Use eclipse glasses and solar projectors

To view the eclipse, wear approved eclipse glasses or use a portable solar viewer. Separately, you can observe the Sun using a telescope, binoculars or a camera with a lens Special solar filter on the frontwhich work in the same way as eclipse glasses.

“You need a degree ISO 12312-2 Compatible solar eclipse glasses. “There are a lot of secure vendors online,” said Alex Lockwood, strategic content and integration lead for NASA Headquarters' Science Mission Directorate. “We cannot stress enough how important it is to have a pair of certified safe solar eclipse glasses in order to view this annual event.”

Sunglasses will not work in place of eclipse glasses or solar projectors, which are 100,000 times darker and meet international safety standards.

The lenses of solar eclipse glasses are made of a black polymer, or resin filled with carbon particles, that blocks almost all visible, infrared and ultraviolet light, according to Planetary Society. Sunglasses do not block infrared rays.

For safe manufacturers and sellers of Eclipse glasses and filters for optical devices, including cameras and smartphones, see List sponsored by the American Astronomical Society.

Put on your eclipse glasses before you look up and remember to step away from the sun before taking them off again. Always supervise any children wearing eclipse glasses to make sure they do not take them off while looking at the sun.

If you normally wear glasses, keep them on and place eclipse glasses over them or hold a portable projector in front of them, according to the American Astronomical Society.

Don't look at the Sun through any unfiltered optical device — a camera lens, telescope or binoculars — while wearing eclipse glasses or using a hand-held solar viewer, according to NASA. Solar rays can still burn through the filter on the glasses or viewer, given how focused they are by an optical device, and can cause serious eye damage.

It is also possible to use welding filters to view the eclipse safely because the international safety standard is derived in part from the use of these filters to view the sun.

Welding filters made of tempered glass or metal-coated polycarbonate and with a shade number of 12 or higher allow for safe viewing, but many find shade 13 or 14 to be preferable and similar to wearing eclipse glasses, according to the American Astronomical Society. Just know that the sun will appear green instead of yellowish-orange or white. These filters are not usually available off the shelf in supply stores, but may be available online.

Auto-darkening or adjustable welding helmets are not recommended because they may not darken quickly enough to see the sun.

As long as the eclipse glasses or solar projectors you use comply with the ISO 12312-2 safety standard and are not torn, scratched, or damaged in any way, they do not “expire” and can be used indefinitely. There is also no limit to how long you can see the sun while wearing it.

Some eyeglasses and viewers carry outdated warnings about using the glasses for more than three minutes at a time or advising that they be disposed of after more than three years, but that does not apply to viewers certified to ISO 12312-2, according to the American Astronomical Society. .

Preserve your eclipse glasses and viewers for future eclipses by storing them at room temperature in an envelope or in their original packaging to avoid scratches.

Never use water, glass cleaner, baby wipes, or any other wet wipes to clean eclipse glasses – moisture can cause the cardboard frames to separate from the lenses. Instead, wipe the lenses carefully with a tissue or cloth.

If you don't have certified glasses on hand, the eclipse can also be viewed indirectly using… Pinhole projector, like a hole punched in an index card. This works when you stand with your back to the sun and raise the card. The hole projects the image of the crescent or sun in the form of a ring onto the ground or other surfaces.

But never face the sun and look at it directly through the hole.

Other pinhole projectors you already have on hand include strainers, straw hats, or anything with small holes. Or you can simply raise your hands, spread your fingers apart, and cross them over each other to create a waffle pattern. The small space between them will reflect the sun's crescent during a partial eclipse or a ring during an annular eclipse.

Standing next to a leafy tree? Small spaces between the leaves will cause eclipse phase patterns to appear on the ground.

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