Can We Use Sunglasses to Watch Solar Eclipse?
The solar eclipse may probably be the only time when you can see just the outline of the sun for a brief period. It appears like an illuminated ring as the moon moves over the sun and covers it completely showing only the edges. Then, can you directly stare at the glare because it is covered? Or maybe wear a pair of sunglasses to watch the scorching sun engulfed by the cool moon?
The obvious answer any eye specialist would give is a big no. It is never safe to gaze directly at the sun. Other than a quick peek at the sun during a solar eclipse, staring at it can pose a high risk of blinding your vision and even damaging your eyes. Of course, there are ways to watch it indirectly or with special glasses approved for the solar eclipse.
So, what happens during a solar eclipse? Why is it dangerous to stare directly into the sunlight even though the brightness seems to be reduced?
This article analyzes the implications of the solar eclipse on your eyes and recommends the correct approach to watching a solar eclipse and witnessing a rare stunning astronomical show.
What Happens During Solar Eclipse?
A solar eclipse occurs when the moon moves between the sun and the earth, causing the moon to either partially (partial eclipse) or completely (total eclipse) block the sun for a brief period of time.
As the moon moves in front of the sun, one bright spot subsequently disappears completely, leaving the sun's atmosphere visible all around the moon, giving the impression of a massive illuminated bracelet or ring. This bright spot may disintegrate into several light rays that glow around the moon's edges as it continues to move.
These are the sun's rays of light passing around on the horizon of the moon and are known as Baily's Beads. They may not last long enough for all observers of the total solar eclipse to notice them because they are very momentary.
However, it is still dangerous to look at the sun at this point. You shouldn't look directly at the sun until all of these spots have vanished.
INFO: Minimum of four eclipses occurs in a calendar year, two solar and two lunars. There were seven in 1982.
You can safely view the total eclipse once Baily's Beads have faded away and there is no longer any sunlight coming directly at you. But even so, you must remain watchful to ensure you shield your eyes once more before the total eclipse ends. In some places, the totality could last just a minute or two.
As the moon proceeds to move across the face of the sun, you will notice lighting up on the opposite side from where the illuminated ring lit up at the initial phase of the eclipse. This is the sun's lower atmosphere bulging out from behind the moon, and it is your cue to stop staring straight at the eclipse. This is the most dangerous phase.
Before the first spark of sunlight appears around the edges of the moon, make sure you have your safety glasses back on.
TIP: You can watch the eclipse through a safe, indirect method at this stage.
Now the process resets. After taking adequate safety precautions, you may continue to watch the eclipse's final stages. Here the end process mirrors the beginning. You will see Baily's Beads again, followed by an illuminated ring. And then the entire sun is visible again.
Implications of Solar Eclipse
Staring at a solar eclipse can result in a burned retina, known as Solar Retinopathy or Solar Maculopathy, which can lead to permanent vision loss.
Dr. Ralph Chou, associate professor of optometry, says in an article published by NASA, "The concern over improper viewing of the sun during an eclipse is for the development of 'eclipse blindness' or retinal burns".
Children and young adults, according to Chou, are most at risk because bright glare and radiation from the sun can cause "heating and cooking of the exposed tissue of the eye". In older people, the aging process can provide a natural filtering effect, lowering the risk of retinal damage.
Can Sunglasses Protect From Solar Eclipse?
Whether you choose to watch a solar eclipse from your home, a hotel, or a beach, you must fully realize how to watch a solar eclipse without impacting your eyes. According to the American Academy of Ophthalmology, using specialized solar filters is the only safe way to look directly at the sun.
Just any sunglass would seldom provide any protection against damaging glare from sun rays. Nevertheless, there are high-end sunglasses with 100% UV protection and polarized lenses. Unfortunately, none of these glasses can be of any use to watch a solar eclipse.
The fact is the most expensive sunglasses cannot shield your eyes during a solar eclipse. Interestingly, certified solar eclipse glasses that can solve this problem are actually inexpensive. These are disposable glasses for safe direct viewing of the sun during a solar eclipse. You need to ensure that these shades are certified to meet the ISO-12312-2 international standards.
Except for the absence of red and blue lenses, these glasses remarkably resemble the 3D glasses you wear to the movies. With eclipse glasses, your retina won't be harmed by harmful rays because the lenses are more reflective and darkened.
A method known as "pinhole projection" is another safe way to view a solar eclipse if you are unable to buy ISO-certified eclipse glasses in time. Using materials like leaves or your fingers to reflect the sun's light onto another surface instead of looking directly at it through a smaller opening is the correct way to view the sun.
Recommendation for Safely Viewing a Solar Eclipse
Even very dark sunglasses or homemade filters are not safe for use when looking at the sun because they transmit far too much UV light. The American Astronomical Society (AAS), a division of the National Science Foundation, provides the following advice for viewing solar eclipses safely:
- Avoid staring directly at the sun.
- Never use regular sunglasses, even those that are very dark.
- Remove your filters after you’ve finished looking at the sun, but do not do so while you're still looking at it.
- Keep your eyeglasses on if you usually wear them. Place a handheld solar viewer in front of them or put on your solar eclipse glasses over them.
- Never use solar filters with cameras, telescopes, binoculars, or other optical devices as concentrated solar rays can damage the lenses and could result in serious eye damage.
- Use specialized solar viewers such as eclipse glasses or a handheld solar viewer.
- Before using your solar filter check for any damage or scratches and discard them if found any.
- If the filters are ISO-compliant they can be used repeatedly as long as they are not scratched, punctured, or torn.
- Abide by the filter's instructions and supervise your kids.
- The safest way to view the sun indirectly is through a pinhole.
Whatever method you use, keep in mind that sunglasses will not provide the necessary protection to watch this rare but damaging occultation. In order to fully experience a solar eclipse, you will need to spend some money on disposable glasses and spare a few moments looking like a space alien.