A total solar eclipse will sweep across parts of the United States, Canada and Mexico on Monday, April 8, 2024, plunging millions of people into midday darkness.
There are four different types of solar eclipses, according to NASA: total, annular, partial and hybrid. A total solar eclipse occurs when the moon passes between the sun and Earth, completely blocking the sun.
If you miss this year’s spectacle, you’ll have to wait 20 years until the U.S. is in the path of the next one. But that total eclipse will only be visible in Montana and the Dakotas.
While it’s exciting to watch these rare events, looking directly into the sun can damage your eyes. We’re VERIFYING four ways to safely watch the total solar eclipse.
THE SOURCES
- NASA
- National Park Service
- American Astronomical Society
- The Exploratorium, a museum of science, technology, and arts in San Francisco, California
- Hin Cheung, Ph.D., O.D., clinical assistant professor at the Indiana University School of Optometry
WHAT WE FOUND
1. It’s safe to watch through special-purpose solar filters, like eclipse glasses or a handheld solar viewer
All of our sources say the only safe way to look directly at the sun during a total solar eclipse is through special-purpose solar filters, like eclipse glasses or handheld solar viewers.
Be sure to always inspect your eclipse glasses or handheld solar viewer before use. If torn, scratched, punctured or otherwise damaged, NASA and the American Astronomical Society both say to discard the device. Also, be mindful that eclipse glasses are not the same as regular sunglasses.
“No matter how dark, regular sunglasses are not safe for viewing the sun,” NASA says.
If you normally wear eyeglasses, the American Astronomical Society says you can keep them on during the solar eclipse and put your eclipse glasses over top of them.
During the eclipse, the American Astronomical Society says to stand still and cover your eyes with your eclipse glasses or handheld solar viewer before looking up at the bright sun. After looking at the sun, you should turn away before removing your eclipse glasses or solar viewer — do not remove them while looking at the sun.
Reputable eclipse glasses and handheld solar viewers should comply with the ISO 12312-2 international safety standard. Filters that are ISO 12312-2 compliant not only reduce visible sunlight to safe and comfortable levels but also block all but a tiny fraction of solar ultraviolet (UV) and infrared (IR) radiation.
The National Park Service says all solar filters that are ISO 12312-2 certified should have the manufacturer’s name and address printed somewhere on the product. However, scammers may copy this label so the American Astronomical Society says the best thing to do is purchase one from a reputable vendor. The Exploratorium recommends that you do not buy eclipse glasses on Amazon or other third-party sites.
“Unscrupulous people have been selling glasses that do not meet the international standard for filters that allow for direct viewing of the sun (even though they are sometimes marked as such). These counterfeit glasses could damage your eyes,” the Exploratorium says.
The American Astronomical Society shares tips on how to spot counterfeit and fake eclipse glasses and a list of reputable solar eclipse viewer and filter vendors on its website.
2. Looking directly at the sun is unsafe, except when the sun is completely covered
It is never safe to look directly at the sun with the naked eye, according to the Exploratorium, because excess UV radiation from the sun can damage the eyes. That’s why it’s necessary to use special-purpose solar filters to watch a solar eclipse.
However, the National Park Service says a total solar eclipse is the only type of solar eclipse where viewers can momentarily remove their solar filters for the brief period of time when the moon completely blocks the sun and it gets dark, which is known as the total phase.
But the American Astronomical Society says this only happens if you’re inside the narrow path of totality. Click here to see if you’ll be in the path of totality on April 8.
“You can view the eclipse directly without proper eye protection only when the moon completely obscures the sun’s bright face – during the brief and spectacular period known as totality,” NASA says. “You’ll know it’s safe when you can no longer see any part of the sun through eclipse glasses or a solar viewer.”
The total phase only lasts two to four minutes, depending on your location in the viewing path, according to the National Park Service. As soon as the bright sun begins to reappear, the federal agency says you should reapply your eclipse glasses or handheld solar viewer to watch the remaining partial phases of the eclipse.
Also, if you are watching an entire eclipse outside, you may be in direct sunlight for hours. NASA recommends wearing sunscreen, a hat and protective clothing to prevent skin damage because the sun will be very bright.
3. Do not look at the sun through a camera lens, telescope, binoculars or another optical device
NASA and the National Park Service say to never look at the sun through an unfiltered camera, telescope, binoculars or other optical device. That’s because these devices require different types of solar filters that must be attached to the front of the device in order to safely watch a solar eclipse.
“Viewing any part of the sun through a camera lens, binoculars or a telescope without a special-purpose solar filter secured over the front of the optics will instantly cause severe eye injury,” NASA says.
So long as the camera, telescope or other optical device is equipped with a proper solar filter, you don’t need to wear eclipse glasses or use a handheld solar viewer while looking at the solar eclipse. NASA says these solar filters do the same job as the eclipse glasses to protect your eyes.
NASA recommends seeking expert advice from an astronomer before using a solar filter with any of these optical devices.
4. You can watch the eclipse using an indirect viewing method
If you don’t have eclipse glasses or a handheld solar viewer to watch the total solar eclipse, NASA recommends using an indirect viewing method, such as a pinhole projector. A pinhole projector is an object with a small opening that projects an image of the sun onto a nearby surface.
Pinhole projectors can be made using several household items, such as a cardboard box or an index card with a hole punched into it. You could also use a pasta colander, a straw hat or anything else with a bunch of small holes in it, according to the American Astronomical Society.
Hin Cheung, Ph.D., a clinical assistant professor at the Indiana University School of Optometry, suggests forming a waffle pattern with your fingers to make your own pinhole projector.
“With your back toward the sun; the small holes between your fingers form a pinhole effect, and that projects an image of the sun on the ground. As the eclipse occurs, you’ll see the projected image of the sun going from round to a crescent shape,” Cheung says.
NASA notes to make sure you do not look directly at the sun through the pinhole. The Exploratorium shares more tips on how to make other do-it-yourself pinhole projectors on its website.
The Associated Press contributed to this report.
This story is also available in Spanish / Lee este artículo también en español: Cómo mirar el eclipse solar con seguridad: 4 Datos Breves
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