Times Internet Limited. All rights reserved. For reprint rights. Times Syndication Service. Prabhjote Gill. If you notice symptoms after viewing a solar eclipse, seek treatment from an eye care professional.
The only time that you can safely view a solar eclipse without special equipment is during a total solar eclipse. This is when the moon completely covers the sun. It is never safe to look at a partial solar eclipse without proper safety equipment or techniques. During the very brief time the sun is in total solar eclipse it is safe to look at it, but do so with caution. Even during the total solar eclipse, the total eclipse may last only a short period of time, and if you are looking towards the sun as the moon moves away from blocking the sun, you might get a solar burn on your retina which can cause permanent damage to your eyes.
Talk with your eye care professional to determine the best viewing option for you. Below are a few common ways to safely watch a solar eclipse:. Pinhole projection : This is the safest and most inexpensive way to watch a solar eclipse.
This helps you avoid looking directly at the eclipse by using a projected image. This do-it-yourself project includes making a pinhole in a cardboard paper with the sun on one side and a piece of paper three feet away without obstruction to project the image on the other side. Keep in mind not to look through the pinhole at the sun. This glass will reduce the harmful rays that are emitted during the eclipse.
Binoculars or a good telescope mounted on a tripod can also be used to project a magnified image of the sun onto a white card. The farther away the card, the larger you can focus the image. Look for sunspots. Notice that the sun appears somewhat darker around its limb or edge. This method of solar viewing is safe so long as you remember not to look through the binoculars or telescope when they are pointed toward the sun; put another way, never look directly at the sun when any part of its blindingly bright surface is visible.
A variation on the pinhole theme is the "pinhole mirror. Open a sun-facing window and place the covered mirror on the sunlit sill so it reflects a disk of light onto the far wall inside.
The disk of light is an image of the sun's face. The farther away from the wall is the better; the image will be only 1 inch across for every 9 feet or 3 centimeters for every 3 meters from the mirror.
Modeling clay works well to hold the mirror in place. Experiment with different-sized holes in the paper. Again, a large hole makes the image bright, but fuzzy, and a small one makes it dim but sharp. Darken the room as much as possible. Be sure to try this out beforehand to make sure the mirror's optical quality is good enough to project a clean, round image. Of course, don't let anyone look at the sun in the mirror. If you're around leafy trees, look at the shadow cast by them during the partial phases.
What do you see? Is it worth a photograph? You will see scores of partially eclipsed suns projected through pinhole gaps between the leaves. This is caused by diffraction, a property of light.
According to Vince Huegele, an optical physicist at the NASA Marshall Space Flight Center, the light rays do not shoot straight by the rim of the gaps, or a pinhole, but bend around the edge. This wave effect creates a pattern of rings that resembles a bull's eye.
If you want to get all set up for it, we have guides to the best cameras for astrophotography , and the best lenses for astro , so you can be well prepared when the time comes. Acceptable filters for unaided visual solar observations include aluminized Mylar. Some astronomy dealers carry Mylar filter material specially designed for solar observing. Also acceptable is shade 14 arc-welder's glass, available for just a few dollars at welding supply shops.
Unacceptable filters include sunglasses, old color film negatives, black-and-white film that contains no silver, photographic neutral-density filters and polarizing filters. Although these materials have very low visible-light transmittance levels, they transmit an unacceptably high level of near-infrared radiation that can cause a thermal retinal burn.
The fact that the sun appears dim, or that you feel no discomfort when looking at the sun through these types of filters, is no guarantee that your eyes are safe. There is one time when you can safely look directly at the sun: during a total eclipse, when the sun's disk is entirely covered.
During those few precious seconds or minutes, the magnificent corona shines forth in all its glory surrounding the darkened sun; a marvelous fringe of pearly white light.
It differs in size, in tints and patterns from eclipse to eclipse. It is always faint and delicate, with a sheen like a pale aurora. It has a variable appearance. Both estimate they had glanced up for about 20 seconds or so — each using a different eye. It was only through separate eye exams later that both men learned they had permanently damaged their retinas.
Material from The Washington Post was used in this report.
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