Double-check your safety measures amid solar eclipse mania
You've ordered your eclipse glasses and made your pinhole viewer. All that's left to do is RSVP to a local watch party for the Aug. 21 solar eclipse.
But are you sure you are completely safe? Better double-check.
The American Astronomical Society (AAS), the top association of professional astronomers in North America, recently revised advice for safely viewing the eclipse because of the rise of bogus “eclipse glasses” and solar viewers.
The AAS said it's no longer enough to look for the logo of the International Organization for Standardization, a global organization that sets standards and specifications for products to ensure safety and quality, or labels that indicate whether the device meets standards for viewing the sun directly.
That's because some companies are printing those labels on their products even if the device does not protect against the sun's ultraviolet, visible and infrared radiation, according to the AAS.
The problem is mostly with online vendors, AAS spokesperson Rick Fienberg told the Tribune-Review.
The most reliable way to make sure your glasses are safe is to trace them back to a reputable vendor or brand. The AAS Solar Eclipse Task Force compiled a list of brands, online sellers and brick-and-mortar stores that are selling safe glasses on its website.
“If we don't list a supplier, that doesn't mean their products are unsafe,” Fienberg said in a statement. “It just means that we have no knowledge of them or that we haven't convinced ourselves they're safe.”
Looking directly at the sun could have devastating effects, according to Deepinder Dhaliwal, professor of ophthalmology at the University of Pittsburgh School of Medicine and director of refractive surgery at UPMC Eye Center.
Normally, when you look up at the sun, your pupils constrict, you realize it's too bright and you instinctively look away.
Dhaliwal worries that the eclipse could lull people into looking directly at the sun for too long, since it will appear darker during the eclipse.
“The only time to look directly at an eclipse is when the eclipse reaches totality, which means the moon is completely in front of the sun,” Dhaliwal said.
But that's not going to happen in the Greater Pittsburgh region. Viewers in our area should keep their protective glasses on at all times, she said.
In Westmoreland County, the eclipse — which will occur when the moon moves between Earth and the sun — is expected to begin at 1:10 p.m. and end at 3:55 p.m. The maximum eclipse, when 80 percent of the sun will be blocked locally, should happen about 2:35 p.m.
Looking directly at the sun during the eclipse will cause a burn, Dhaliwal said. Light will pass through the eye and damage the retina. The retina lines the back of the eye, like film in a camera.
“If that film is damaged, it will cause a permanent blind spot forever,” Dhaliwal said.
If you have a pair of specs or a solar viewer, Dhaliwal recommends inspecting the device before use. Check for scratches or tears. If it's damaged in any way, do not use it.
The sun should appear very dull through the glasses. If it seems bright or is difficult to look at, something might be wrong with the glasses.
Even if you have glasses, remember that it's still not safe to look at the sun through a pair of binoculars, a telescope or a camera. Those lenses must also be filtered. A professional-grade filter for a telescope will reflect about 99 percent of the light, said John Smetanka, vice president for academic affairs, academic dean and associate professor of physics at St. Vincent College in Unity.
The filters are about 3 to 4 inches thick and look like a mirror. Most of the sun's light is reflected off the filter, with only a small fraction allowed through.
“Even if you're blocking out 99 percent of the sunlight, that's still 1,000 times brighter than the full moon,” Smetanka said.
Jamie Martines is a Tribune-Review staff writer. Reach her at 724-850-2867, firstname.lastname@example.org or via Twitter @Jamie_Martines.