It is imperative to protect your eyes from the sun when viewing the eclipse, as the sun's rays are so concentrated that without protection, they will concentrate in the back of the eye and damage the retina. This damage is sometimes not noticed until hours or days later and can manifest as seeing straight lines as wavy, noticing a spot in vision, and blurred vision. To protect your eyes, use a certified viewing card, or use alternative methods such as pinhole projectors or finger lacing.
It is very dangerous to look at the sun during an eclipse because the sun outputs more power than our eye can handle, which damages the retina. There are certain methods you should not use to view an eclipse:
- Any type of glasses or sunglasses
- Smoked glass
- Polarizing filters
- Exposed color film
None of these methods are strong enough to protect your eyes from permanent damage. These methods do block visible light from damaging the eye, but does not protect against non-visible light, such as ultraviolet and infrared light.
Safety glasses available on campus
Indiana University will be handing out 10,000 pairs of solar eclipse viewing cards at First Year Experience Guide Tables and at the Conrad Prebys Amphitheater on a first come, first serve basis. IU will also offer suggestions on how to view the eclipse indirectly to ensure that everyone on campus can view the eclipse safely. For those who will not be watching with us, there are a couple home-made devices, such as pinhole projectors, that can be used to view an eclipse safely or it is safe to use number 14 welder's glass or darker.
Partial versus total eclipse safety
It is never safe to look directly at a partial eclipse. Even though half the sun is covered, it does not mean that it is half as dangerous to look up! The UV rays emitted from the sun are still equally as dangerous as it would be to look at the sun directly. In order to ensure eye safety and protection of the retina, one must look at a partial eclipse via safety glasses or projecting the images via a pinhole camera or shadows from the trees!
However, during a total eclipse (which will not be viewable in any part of Indiana), during totality- or, when the sun is completely blocked by the moon (which will only happen in a narrow portion of the eclipse path) - is safe to look at because the moon effectively blocks the sun’s rays.
The safety of watching a total eclipse is only for a brief minute, and then the rays become dangerous to the eye. While it is technically safe to look at the exact moment of totality, it is recommended not to! The sun can become dangerous in milliseconds, even during totality. Better safe than sorry: do not look directly without protection!