There has been a lot of press lately about safely viewing the August 21 solar eclipse. The bottom line is that only the 2.5-ish minutes of totality are safe to observe with your unaided eyes (and the eclipse will NOT be total in Connecticut!). Those of us in the partial eclipse zone should NEVER look directly at the sun without proper eclipse glasses! If you want to be 100% safe, use a pinhole projection system, such as the box pictured above, or to watch it on television or on the internet.
If you want to use eclipse glasses, remember the bottom line is that the safe use of eclipse glasses is YOUR responsibility. The following are steps that I use in my own eclipse viewing:
- Make sure your eclipse glasses are obtained from a reputable source. Note that this is merely one step in the process and by itself cannot guarantee your eye safety! The glasses must have labeling that says “safe for direct solar viewing” or “safe for direct viewing of the sun.” Glasses need to meet the ISO 12312-2 standard adopted in 2015 (these glasses block UV and IR as well as visible light). The AAS (eclipse.aas.org) has a list of some reputable sources (be sure to read their various notes and disclaimers). Updated: There are apparently bootleg glasses on the market that claim to meet these standards (and their websites make false claims). Make sure you only buy eclipse glasses from reputable sources (such as a museum or science center). There are many libraries and amateur astronomy groups that are handing out free glasses as well.
- Inspect the eclipse glasses for any defects or damage both when you initially receive them and, most importantly, RIGHT BEFORE you use them. Make sure that the filter material is not loose or compromised in any way. Inspect the filter material for cracks, creases, holes, tears, gaps, or other problems. Hold the glasses up to a light (NOT THE SUN) and look for any pinpricks or other defects that let light through. If you see any of these defects, immediately destroy the glasses and throw them away.
- Do not use the eclipse glasses with any optical aid except your contact lenses or eye glasses. The eclipse glasses are shaped that way because they are only meant to be used with your eyes. Do not use them with cameras, binoculars or any other optical aid. Wear them over your regular eyeglasses.
- Put your eclipse glasses on BEFORE you look up at the sun. Place your eclipse glasses on, fully covering your eyes, before you look up at the sky. At this point you should not be able to see anything through the eclipse glasses – everything should look black. Once you have them firmly in place, look up in the direction of the sun. Do not remove your eclipse glasses until you are looking down toward the ground again. Do not look at the partial phase with just your eyes, or through clouds. This applies whether the eclipse is 10% partial or 99% partial! Always supervise children’s use of eclipse glasses at all times. Very young children should probably not use eclipse glasses because of the risk of them taking them off and trying to look directly at the sun. If you have any doubts about their ability to safely use eclipse glasses, switch to pinhole projection immediately.
- Make sure the sun looks sharp and relatively dim when seen through the glasses. The sun should look comfortably dim when seen through the glasses. The image should also be crisp, clear and not have a halo or any other strange effects. If the image looks fuzzy, or you feel it is too bright, look away from the sun immediately, remove the glasses, destroy and discard them. This image shows you how the sun’s image should appear in proper eclipse glasses.
Note that these are merely some steps that I personally take; for more information, see the AAS eclipse website. A detailed report on eclipse safety can be found here. Again, the ultimate responsibility for safe eclipse viewing is yours! If you feel uncomfortable in any way with your eclipse glasses, please err on the side of caution and switch to pinhole projection.
Note: This document does not constitute medical advice. Readers with medical questions should contact a qualified eye-care professional.