Without proper safety measures, the solar eclipse set to sweep across the country next week may be the last thing you see.
Looking directly at an uneclipsed or partially eclipsed sun exposes your eyes to intense UV radiation and irreparable damage. The same is true of viewing the sun through an unfiltered camera, telescope, binoculars or other non-certified optical device.
The only safe time for people to look up during the eclipse will be during a short period when the moon will totally block the sun's rays. Central Ohio falls far outside the eclipse's narrow path of totality. Here, the moon will cover 86.3 percent of the sun during the event's peak. But NASA warns that anything less than 100 percent coverage of the sun's surface during the eclipse is intense enough to cause retinal burn — even if you cannot feel the damage to your eyes.
>> Special coverage | Solar eclipse: The day the sky goes dark
“You feel like you can look away if you need to,” said Dr. Michael Earley, a practicing optometrist and associate dean for academic affairs at Ohio State's College of Optometry. "But the damage will already be done.”
What’s the worst that could happen?
If you get a hankering on Aug. 21 to turn a naked eye toward the sun — don’t.
Should the urge persist, Earley suggests imagining how a magnifying glass on a sunny day can fry ants, light kindling and burn through a leaf.
“Well, the eye is stronger than a typical magnifying glass, if that gives you an idea,” he said. “When you point it right at the sun, your vision can go from 20/20 to 20/200."
An intense shot of UV light will do more than thermally burn your eye tissue; it can also wreak photo-chemical havoc in the part of the retina responsible for high-detail vision.
“If you permanently damage cells in your retina, they will not regenerate,” Earley said. “Before you actually feel the burn, you’ve already done cellular damage. For the rest of your life, you’ll very likely end up with less vision.”
Are there no-nos for solar-eclipse viewing?
To be clear: sunglasses, 3-D-movie glasses and scratched or wrinkled old eclipse glasses will not safeguard your vision.
And when shopping for safe solar-eclipse eyewear, look for manufacturers that have certified that their glasses and hand-held solar viewers meet the ISO 12312-2 international standard for such products. Stay away from "eclipse glasses" lacking a clear ISO stamp of approval.
Unfiltered cameras, telescopes and binoculars will do nothing to protect your eyes.
To demonstrate the risk of exposing an eyeball to magnified sunlight, Don Stevens of Ohio Wesleyan University's Perkins Observatory will hold up a pine cone to the eyepiece of a telescope pointed at the sun. Spoiler: it bursts into flame.
“Because your eyeball is wet and squishy, it would flash-boil the fluids in your eye and explode them out of the socket,” Stevens said. “It would be the last thing you see.”
What’s my best option for safe viewing?
While supplies last, you can buy $3 eclipse glasses at all Half Price Books locations in central Ohio. Proceeds from the sales will go toward renovating Perkins Observatory.
After a first order of 1,000 glasses sold out in days, the five regional stores have been stocked with 5,000 more pairs of the specialty eyewear, said district manager Chris Heuing.
“We’ve beefed it up,” Heuing said. “You know you’re getting the right stuff if we're partnering with the observatory. They’re the experts.”
The American Astronomical Society has compiled a list of reputable vendors selling compliant glasses or hand-held viewers, including Kroger, Wal-Mart Stores, REI, Lowe's and Best Buy.
On the day of the eclipse, COSI will distribute free glasses on Ohio State University's Oval and at viewing parties at some Metro Parks and public-library sites.
Can I make something to view the eclipse?
Maybe you waited too long to get your hands on a Sunspotter, Solarscope or Sun Funnel.
Maybe you're inventive. Maybe you’re just cheap.
In any case, you can safely view the partial eclipse without specialty equipment or modified telescopes or binoculars. All it takes to make a pinhole camera is two sheets of stiff white paper and a pin.
First, punch a hole in the center of one of the sheets and aim it at the sun. (It probably goes without saying, but don’t look at the sun though the hole. Remember: flaming pine cones and scorched ants and exploding eyeballs!)
Then, move the other piece of paper around until a clear projected image of the sun appears on it.
As a last resort, you can use your bare hands. Spread your fingers apart and overlap them to create a loose grid. When you look at your hands’ shadow on the ground, the spaces between your fingers should project a cluster of crescents during the eclipse’s partial phases.