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A stunning total solar eclipse will be visible to millions of people in Mexico, the United States and Canada on April 8.
Astronomers are encouraging anyone along the way to enjoy this rare sight for the last time by August 2044 – but only if they can do so safely. And sunglasses won’t be enough to protect your eyes in this celestial event.
A total solar eclipse occurs when the Moon comes between the Earth and the Sun, completely blocking the Sun’s face.
Those on the path of totality or places where the moon’s shadow will completely block the sun will see a total solar eclipse. People outside the path of totality will still be able to see a partial solar eclipse, where the moon covers only part of the sun’s face.
If your location can only view a partial solar eclipse, some of the sun’s strong light will always be visible. And seeing the sun’s brightness with the naked eye is not only uncomfortable, but also dangerous.
Why you shouldn’t look directly at the eclipse?
According to NASA, the only time it is safe to see the sun without eye protection is during the “totality” of a total solar eclipse, or the brief moments when the moon completely blocks sunlight.
Looking directly at the sun can cause blindness or visual impairment. During a total solar eclipse in 2017, a young woman was diagnosed with solar retinopathy (damage to the retina due to exposure to solar radiation) in both eyes after viewing the eclipse with eclipse glasses that did not meet doctors’ safety standards.
There is no cure for solar retinopathy. It may get better or worse, but it is a permanent condition.
Using eclipse glasses and solar imagers
Wear certified eclipse glasses or use handheld sunglasses to view the eclipse. Separately, you can observe the sun with a telescope, binoculars, or a camera with a special solar filter on the front that acts like eclipse glasses.
“You need certified solar eclipse glasses that comply with ISO 12312-2. There are many safe vendors online,” said Alex Lockwood, strategic content and integration leader for the Science Mission Directorate at NASA headquarters. “We cannot emphasize enough how important it is to get a pair of safe certified solar eclipse glasses to witness this annular event.”
Sunglasses will not work as a substitute for eclipse glasses or sunglasses, which are 100,000 times darker and comply with the international safety standard.
The lenses of solar eclipse glasses are made of black polymer, or resin infused with carbon particles, that blocks nearly all visible, infrared and ultraviolet light, according to The Planetary Society. Sunglasses do not block infrared radiation.
For safe manufacturers and vendors of Eclipse glasses and filters for optical devices, including cameras and smartphones, check out the list compiled by the American Astronomical Society.
Put on your eclipse glasses before looking up, and remember to move away from the sun before taking them off again. Always keep an eye on children wearing eclipse glasses to make sure they do not take them off when looking at the sun.
If you normally wear glasses, put them on and place eclipse glasses over them or hold a hand-held viewer in front of them, according to the American Astronomical Society.
According to NASA, do not look at the sun with any unfiltered optical device (camera lens, telescope, binoculars) while wearing eclipse glasses or using a handheld solar viewer. Considering how concentrated they can be in an optical device, the sun’s rays can still burn and cause serious eye damage by getting through the filter on glasses or goggles.
It is also possible to use source filters to safely view the eclipse because the international safety standard is derived in part from the use of such filters to view the sun.
Source filters made of tempered glass or metal-coated polycarbonate and having a shade number of 12 or higher allow safe viewing, but most people consider shade 13 or 14 to be best 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 found off the shelf at supply stores, but they may be available online.
Auto-darkening or adjustable welding helmets are not recommended as they may not darken quickly enough to see the sun.
hide your glasses
As long as the Eclipse lenses or sunglasses 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 them.
Some glasses and trackers carry outdated warnings against using the glasses for more than three minutes at a time or recommending that the glasses be discarded after more than three years, but these do not apply to ISO 12312-2 certified glasses, according to the American Astronomical Society. .
Store your Eclipse glasses and trackers for future eclipses by storing them in an envelope or original packaging at room temperature to prevent scratches.
Never use water, glass cleaner, baby wipes or other wet wipes to clean Eclipse windows; Moisture can cause the cardboard frames to separate from the lenses. Instead, carefully wipe the lenses with a tissue or cloth.
Indirect viewing of the eclipse
If you don’t have certified glasses on hand, eclipses can also be viewed indirectly using a pinhole projector, such as a hole punched in an index card. These work when you have your back to the sun and lift the card. A pinhole projects an image of the sun in the shape of a crescent or ring onto the ground or other surfaces.
But never look at the sun and never look at it directly through the eye of a needle.
Other pinhole projectors you may have on hand include strainers, straw hats, or anything with small holes in them. Or you can hold your hands up, spread your fingers apart, and stack them on top of each other to create a waffle pattern. The small gap in between will reflect the sun’s crescent shape during a partial eclipse or a ring during an annular eclipse.
Are you standing next to a leafy tree? Small spaces between leaves will stain patterns of the eclipse phase on the ground.
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