The multiple warnings about not looking directly at the sun seem peculiar.
I mean, really? “Don’t look at the sun” is akin to “don’t hold your hand over a flame” or any other dangerous and painful act that would be ludicrous to do and impossible to sustain. Common sense dictates against such a practice (but judging from recent events in our culture, common sense is at a premium).
I couldn’t help but wonder (Carrie Bradshaw style)…is this really a problem? Turns out it is. According to LiveScience.com, total blindness is rare, but you might be in danger of contracting “solar retinopathy”—aka photic retinopathy, foveomacular retinitis, solar retinitis, and eclipse retinopathy—resulting in temporary to permanent blurriness or a blind spot at the center of your vision.
“Eclipse blindness” is caused when ultraviolet light overwhelms your retina, located at the back of your eye where the photosensing cells that allow you to see are located. During the deep partial phases of the eclipse when sunlight dims it can be tempting to sneak a peek, and the damage at that point is delivered without pain and when protective reflexes (like blinking and pupil contraction) are slacking off.
Solar retinopathy can occur at any point during the partial phase—including the final seconds before totality—and the most important reason to shield your eyes occurs in the very last two or three seconds before blackout: looking directly at the sun during this time can cause temporary vision distortion that can bork your enjoyment of the scant, precious minutes of totality.
Many people don’t understand that you must look at the sun with the naked eye after Second Contact, and the trick for a first time eclipse viewer is to know when to whip those eclipse shades off in time to see the entry phenomenon like Bailey’s beads and the diamond ring. Stay calm, and keep your glasses on until you’re sure it’s safe. (The sound effects coming from those around you will alert you that totality has occurred.) Rest assured that you’ll get a good long look at the ring and the beads in reverse order at Third Contact. Don’t risk blurry eyesight during the big event by removing your shades too soon.
It’s optimal if there’s a coach in the area to let you know what to do. This video is an example of the phenomena countdown by Jay Anderson, meteorologist aboard the expedition ship Orion in the Great Barrier Reef with (TravelQuest, Nov. 13, 2012). Some find spoken words distracting, but I think it adds to the thrill.
I love looking at the eclipse safety posters and flyers that local governments distribute—like the ones at the end of this post.
The only safe way to look directly at the partially eclipsed sun is through special purpose filters such as “eclipse glasses” or my uber-dorky #14 welder’s goggles.
The popular paper eclipse glasses you’ve seen are made with optical density 5 “black polymer” material that filters out harmful ultra-violet, infrared, and intense visible light. Look for brands made in the USA (beware of overseas knock-offs) and that state they are CE certified and meet ISO standards. I recommend Rainbow Symphony, manufacturer of our custom Blackout Rally shades. I’m told American Paper Optics and Thousand Oaks Optical are two other reliable manufacturers.
What’s true for your eyeballs is true for the devices you look through. Do not look at the uneclipsed or partially eclipsed sun through an unprotected camera, telescope, or binoculars—and don’t use these things while wearing your eclipse shades, either. The intensified solar rays will damage the filter and enter your eye. (Gad, this is getting scarier and scarier, isn’t it? You’’ll be happy to know that your own prescription eyeglasses are safe to use with eclipse shades or a solar-filtered telescope.) Both your eyes and your optical device need their own filter. Pointing an unprotected telescope directly at the sun can also result in the unfortunate melting of the plastic parts that hold the internal instruments together.
Oh, and don’t make your own filter like some hillbilly. Black plastic trash bags, balloons, camera film (WTF is that), or three pairs of sunglasses worn together won’t bar ultraviolet light.
Eclipse shades make a great souvenir of the experience; I have a small collection and the ones from Egypt are my favorite.
You’ll be able to put your hands on a pair of eclipse shades pretty easily before August 21, but order online soon. Alternatives to the standard style include hand-held viewers, magnification viewers (like the Celestron EclipSmart™ power viewer) and even wacky ones that let you look like an astronaut or an alien.
The weakest technique of all is the pinhole projection, but it’s fun to do to pass the time during the boring partial phases before and after totality. Here’s how:
- Use two sheets of cardboard (stiff white paper, even two paper plates)
- Make a tiny, round, smooth hole in the middle of one sheet using a thumbtack, a sharp pin, or a needle
- Stand with your back to the sun, and hold up the paper with the hole.
- The second sheet of paper serves as a screen for the projected image. Do you see a little crescent shadow? That’s the inverted image of the sun coming through the pinhole.
- Experiment: make the image of the sun larger by moving the pinhole paper closer to the sun.
- Anything with “holes” can be a pinhole projector: a straw hat, your loosely crossed hands, etc. Find a nearby tree and look at the ground below: the leaves will create hundreds of crescent projections.
Check out this excellent 4+ minute video courtesy of the American Astronomical Society (AAS) Solar Eclipse Task Force and the American Institute of Physics. It will tell you everything you need to know about eclipse safety.
Above: #14 welder’s glasses. Below: Blackout Rally shades; Egypt souvenir (what does that hieroglyphic say, “scram, tourist”?); handheld viewer, solarscope (I have no idea what this does); PowerViewer; alien shades; pinhole hands.