The most important thing to consider when planning for a solar eclipse isn’t your location within the path of totality, your distance to the centerline, or even the weather. It’s eye safety. If you attempt to view an eclipse incorrectly, there’s a really great chance your souvenir of the eclipse will be irreparable eye damage or even blindness. We all want to make lifelong memories on August 21, but those memories should be indelibly imprinted onto our minds, not our retinas.
Unfortunately, the media sometimes neglects to mention the importance of solar eclipse eye safety and occasionally they even unwittingly provide incorrect or dangerous information. Recently, one of the largest media companies in the world suggested that people should use sunglasses to view the eclipse on August 21. Of course, ordinary sunglasses are never safe to use for direct solar viewing. Another media outlet encouraged readers to get their binoculars ready for the eclipse and never mentioned the fact that optical devices like cameras, binoculars, and telescopes need specially designed solar filters that fit snugly on the front end (the Sun side) of the device. Attempting to view an eclipse with an unfiltered optical device is like holding a magnifying glass to your eye while focusing direct sunlight through the lens. No, you definitely don’t want to do that.
Our hope is that as we get closer to August 21, the media will take the subject of eye safety more seriously and communicate the proper and safe way to view a solar eclipse as carefully and unambiguously as possible. Too many eyes are at risk not to get this information right every single time. In the meantime, here’s what you need to know to stay safe on August 21:
Use Eclipse Safety Glasses
You must use special eclipse safety glasses or handheld solar viewers to view a partial eclipse, an annular eclipse, and the partial phases of a total eclipse. Although it may be tempting to look directly at an eclipse with unprotected eyes when so much of the Sun is obscured, the small amount of light emitted during even a 99.9 percent partial eclipse is still dangerous. The only time it’s safe to look at a total eclipse without proper eye protection is during the very brief period of “totality” when the Sun is 100 percent blocked by the Moon. If you’re in a location where the eclipse won’t be total, there is never a time when it’s safe to look with unprotected eyes. (For the record, on August 21, we’ll have a total eclipse that will be partial most of the time within the path of totality and partial all of the time outside the path of totality.)
Be Wary of Phony Glasses
Make sure that your eclipse safety glasses and handheld solar viewers are certified as meeting ISO standards for safe solar viewing. The current standard for safe solar viewing is ISO 12312-2; your eclipse glasses and viewers should have this designation printed on them. Take care to purchase your glasses from a reputable seller and be wary of knockoff glasses that claim to be safe but aren’t. Already, there are reports of bogus eclipse glasses made by a company called Solar Eclipse International. Be very careful and don’t use any product unless claims of safety can be verified. We recommend the products made by Rainbow Symphony. You can easily find a variety of eclipse safety glasses and handheld solar viewers made by Rainbow Symphony at online sites like Amazon.com and the NationalEclipse.com eclipse store provides direct links to many of these items. Before using your glasses or viewers, make sure that they are not damaged in any way and that you read all of the safety instructions that came with them. Children should always be supervised when using eclipse safety glasses and handheld solar viewers.
Unless a product has been specifically designed for safe solar viewing and has been certified as meeting international standards for such products, it’s best to assume that a device, method, or instrument is unsafe. Don’t risk it! Items such as regular or polarized sunglasses, smoked glass, exposed film, medical x-rays, homemade filters, and many others are all unsafe. You can use welder’s glass to view an eclipse, but it must be #14 welder’s glass; any rating below #14 is not safe. It’s also safe to view an eclipse using indirect methods, such as projecting an image of the eclipsed Sun onto a white screen. Search online for “pinhole projector” and follow the instructions provided by a trusted organization like NASA to make your own.
Protect Your Eyes Before and After Totality
The eclipse will become total for a very short period of time only in the narrow path of totality. If you’re located in the path of totality, don’t remove your eclipse glasses until the very last bit of the Sun is gone, including “Baily’s beads” and the “diamond ring.” Again, it’s only safe to look with unprotected eyes when the Sun is 100 percent blocked by the Moon and only the soft wisps of the solar corona are visible. Once totality begins, it’s important to know exactly when totality will be ending in your precise location so that you can once again put on your eclipse glasses before the first brightness of the exposed Sun is revealed. The definitive source to determine the exact start time, end time, and duration of totality for any location is NASA’s interactive Google map of the eclipse. It’s also a good idea to allow for a generous margin of error to ensure that you are no longer looking with unprotected eyes when totality ends. As mentioned earlier, children should always be supervised by someone who fully understands safe eclipse viewing procedures.
Optical Devices Must Have Solar Filters
As already noted, attempting to view the Sun using cameras, binoculars, telescopes, or other optical devices without proper filters is extremely hazardous and can permanently damage the eyes in an instant. These devices need specially designed solar filters that fit snugly on the front end (the Sun side) of the device. Never attempt to view the Sun through an optical device using eclipse glasses or any type of filter that attaches to the viewing side (as opposed to the Sun side) of the instrument; the focused light will destroy the filter and enter and damage your eyes. Remember the magnifying glass analogy? Since viewing or photographing a solar eclipse with an optical device requires specialized equipment and knowledge, your best bet is to consult with a qualified astronomer or just enjoy the eclipse with your own eyes using the safe solar viewing procedures already mentioned.
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