Solar Eclipse And Blindness, What To Do And What Not To

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solar eclipse

What is Eclipse?

An eclipse is an astronomical event that occurs only when one celestial body’s shadow falls onto that of another. In the context of earth, we use the term solar and lunar eclipse mostly. Eclipse is derived from an ancient The Greek word that means “to abandon” or  “to darken”. So, what is a solar and lunar eclipse and do they have negative effects on our eyes?

The solar eclipse is a term described as the state when the moon’s shadow falls on the earth’s surface. It happens as the earth moves into the shadow cast by its natural satellite moon. Likewise, Lunar eclipse is defined as the state when the moon comes into the shadow cast by its hosted planet earth. There would be a solar eclipse every month on the new moon and there would be a lunar eclipse on every full moon, but it doesn’t work that way. Even though the moon’s orbit is around the earth, but due to the non-planer and non-circular orbit of the moon around the earth,  eclipses are not a common event.

Solar Eclipse Time in Nepal: June 21, 2020

As per the reports of a science portal, the Solar Eclipse in Nepal will last for approximately 3 hours and 30 minutes. It will commence at 10:53 am and will last until 2:24 pm. Here is what will happen during the Solar Eclipse in Nepal.

  • The partial eclipse will begin at 10:53 am, with the moon touching the sun’s edge.
  • At 12:41 pm the moon will be closest to the centre of the sun. Hence, this will be the point of maximum eclipse.
  • At 2:24 pm, the moon will leave the sun’s edge. Therefore, ending the partial eclipse.

Misconceptions about the eclipse:

Sun emits Extra radiations during the eclipse:

The sun is 15 Million Kilometers from the earth and the moon is 375,000 k.m from the earth. The moon coming between the sun and earth doesn’t alter the nuclear reaction happening in the sun. 

pupil of human eye

There is a small coloured portion in the eye called “IRIS”. The centred hole of which is defined as “pupil”. The major function of the pupil is to regulate the amount of light entering the eye and reaching the retina. During a bright sunny day, the pupil is constricted to allow minimum light in the eye so the retina is not overwhelmed by brightness and damage. Whereas, in the solar eclipse, it is cloudy outside which causes our pupil to dilate. The light enters the eye easily. When people look at the eclipse, regardless of the total or partial eclipse, your pupils are completely dilated and extremely vulnerable. Light enters your pupils and before your brain can comprehend what has happened, a small amount of exposure to direct sunlight can cause permanent damage to your retinas. 

In certain conditions, the outer layers or epithelium of cornea (an outermost transparent portion of eyes) might peel off due to longer solar exposure which later heals by itself without any residual effects. It, however, causes pain until complete recovery.

What to do and what not to?

The solar retinopathy is the term defined for the damage caused to eyes during the eclipse. Avoid looking at the sun directly. Use a dark goggle that protects your eyes from harmful light of the sun. Avoid using cameras or smartphone to look at the eclipse. Don’t view through viewfinder, binoculars or telescopes.

The safest way is to make a DIY project of pinhole projector. Make a hole in a paper and let the light fall on the paper placed on the ground. (Not to be confused with looking eclipse with pinhole). Recorded videos can be watched.

“Keep in mind that ordinary sunglasses, even very dark ones, or homemade filters are not safe for looking at the sun.”

How to View a Solar Eclipse Safely

The only safe way to look directly at the uneclipsed or partially eclipsed Sun is through special-purpose solar filters, such as “eclipse glasses” (example shown at left) or handheld solar viewers. 
NASA recommends Eclipse viewing glasses and handheld solar viewers should meet all the following criteria:
  • Have certification information with a designated ISO 12312-2 international standard
  • Have the manufacturer’s name and address printed somewhere on the product
  • Not be used if they are older than three years, or have scratched or wrinkled lenses
  • Not use homemade filters
  • Ordinary sunglasses — even very dark ones — should not be used as a replacement for eclipse viewing glasses or handheld solar viewers
You can also follow the projection method, to know about projection method: 
Don't watch eclipse with ordinary sunglass

How not to watch a solar eclipse?

Be careful about how you watch a solar eclipse. It is not recommended to view it in the following ways:
Smartphone: Watching a solar eclipse on your smartphone camera can put you at risk of accidentally looking at the sun when trying to line up your camera. It could possibly also damage your smartphone camera. Don’t take the risk.
Camera viewfinder: Never look at a solar eclipse through the optical viewfinder of a camera. It can damage your eyes in the same way as looking directly at it 
Unsafe filters: Unless specifically designed for viewing a solar eclipse, no filter is safe to use with any optical device (telescopes, binoculars, etc). All colour film, black-and-white film that contains no silver, photographic negatives with images on them (x-rays and snapshots), smoked glass, sunglasses (single or multiple pairs), photographic neutral density filters and polarizing filters are unsafe filters to watch a solar eclipse. Also, solar filters designed for eyepieces that come with inexpensive telescopes are also unsafe. All of these items can increase your risk of damaging your eyes.

Eye symptoms that can occur from looking at a solar eclipse without proper eye protection:

  • Loss of central vision (solar retinopathy)
  • Distorted vision
  • Altered colour vision

What if you see blur after you look at the eclipse?

solar retinopathy

The best possible thing to do is to avoid yourself from doing so. The damage is irreversible and Incase you see blurry, you need to visit an Eye Hospital as soon as possible.

Notes and Reference: 

  • National Aeronautics Space Administration, American Academy of Ophthalmology.
Last Updated:  21 June 2020
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