2024 Eclipse Corner #3 Be Safe Looking at the Solar Eclipse

Philip S. Harrington says in his book Eclipse!, “The sun holds the dubious distinction of being the only celestial object that may actually harm someone who looks at it directly.” Your eyes will tell you after a slight glance toward the sun, they turn you away. What makes looking at the sun so dangerous? The sun not only radiates visible light, but its photosphere or surface emits infrared and ultraviolet radiation.

“Just as ultraviolet radiation causes sunburn to exposed skin, so too will it damage your eyes’ retinas. The human eye needs only direct sunlight for a few seconds before permanent eye damage, and even blindness, results. Since there are no pain receptors in the retina, there is no feeling of discomfort as eye damage occurs.”

Totality is the only time when it is safe to look directly at a solar eclipse without protection.

In the NASA Eclipse website, expert Fred Espenak says, “Do not attempt to observe the partial phases of the total eclipse with the naked eye.” Even when 99 percent of the sun’s surface is obscured or covered, the remaining photospheric crescent is intensely bright and cannot be viewed safely without protection. “The responsibility for following all safety precautions in using any suitable viewing equipment or methods and in following proven safe viewing practice, lies solely with the person who owns the eyes that are viewing the eclipse.”

At most sites, groups of watchers, schools and communities are providing inexpensive but safe solar eclipse glasses or handheld solar viewers to view the eclipse. These glasses are made from exclusive scratch resistant, optical density 5, “Black Polymer” plastic type material which has exceeded the rigorous ISO 12312-2: 2015 international standards for safe direct viewing of the sun and to filter harmful infrared and ultraviolet radiation. You can always check. The ISO requirements will be printed on the glasses.

The American Astronomical Society offers tips for viewing the solar eclipse: Always inspect your solar filter or glasses before use, if scratched or damaged, discard it; read and follow any instructions printed on or packaged with the filter; always supervise children using solar filters; stand still and cover your eyes with your eclipse glasses or solar viewer before looking up at the bright sun; after looking at the sun, turn away and remove your filter — do not remove it while looking at the sun. Remove your solar filter only when the moon completely covers the sun’s bright face and it suddenly gets dark. Experience totality, then, as soon as the bright Sun begins to reappear, replace your solar glasses to watch the remaining partial phases. To date, four manufacturers have certified that their eclipse glasses and handheld solar viewers meet the ISO 12312-2 requirements for such products: Rainbow Symphony, American Paper Optics, Thousand Oaks Optical, and TSE 17. As this article was written in advance, more manufacturers may become certified.

Welding glass number 14 (or more) is safe, however, most welding helmets do not usually use that dark of glass. Solar filters from telescopes should be safe, but there is a concern about inexpensive telescope equipment being exposed to multiple minutes of sun heat may cause difficulties. Other bad ideas include dark sunglasses, exposed film, and thick brown beer bottle bottoms. Do not use your eclipse glasses to look through binoculars or telescopes where the magnification of the sunlight has been enhanced and the eclipse glasses have not been. It is not worth risking your eyes. Several methods of projection or indirect viewing will be discussed in later Eclipse Corners.

A new toy, not used in 2017 is the Solar Snap Eclipse App Kit. It gives you two solar camera filters for taking pictures with your phone. Created by Dr. Doug Duncan former Hubble Space Telescope Astronomer, it is safe and innovative.

Some areas will have a horn, siren, or announcement to signify that totality has been reached. Now, it is safe to look at the sun. Put your glasses and observing devices down and enjoy. This is what we have been waiting for - totality. A total solar eclipse is probably the most spectacular astronomical event that most people will experience in their lives.

Dan Slais is a retired earth science teacher from Waynesville, Mo.. He has also taught college Astronomy for Drury and Columbia College.