By now, you’ve probably heard about the enormous celestial event occurring this month: a total solar eclipse. A solar eclipse is, simply put, when the moon acts as a better door than a window, coming between the sun and Earth and casting a shadow somewhere on the earth’s surface. Whereas a partial eclipse happens at least twice a year somewhere on the planet, a total solar eclipse has not occurred since 1979; and the same places on Earth will not see a completely-eclipsed sun for another 375 years! On August 21, cities across the continental US will get their chance for this once-in-a-lifetime experience.

Where to See It

The eclipse will cast a 60-mile wide shadow where the sun will be completely obstructed known as "the path of totality." Stretching across the lower 48 states, a few cities that are included in the solar eclipse path, along with the start and end times of the eclipse, include:

• Madras, Oregon — 9:06am – 11:41am
• Idaho Falls, Idaho — 10:15am – 12:58pm
• Casper, Wyoming — 10:22am – 1:09pm
• Lincoln, Nebraska — 11:37am – 2:29pm
• Jefferson City, Missouri — 11:46am – 2:41pm
• Carbondale, Illinois — 11:52am – 2:47pm
• Paducah, Kentucky — 11:54am – 2:49pm
• Nashville, Tennessee — 11:58am – 2:54pm
• Clayton, Georgia — 1:06pm – 4:01pm
• Columbia, South Carolina — 1:13pm – 4:06pm

Check out NASA’s interactive app to see where your city falls on the solar eclipse path and estimate your eclipse viewing.

See the Danger

This event is incredibly popular, with thousands planning trips to the “path of totality” to catch a glimpse of the phenomenon. Obviously, staring at the sun is never going to be a safe activity, but the damages that can occur during an eclipse viewing can be underestimated. NASA’s Eclipse Web Site states, “Even when 99% of the Sun's surface is obscured during the partial phases of a solar eclipse, the remaining crescent Sun is still intense enough to cause a retinal burn, even though illumination levels are comparable to twilight.”

The sun is normally too powerful and bright for most to stare at directly, but during an eclipse, total or partial, it can become more comfortable, and typical safety reflexes like pupil contraction and blinking are less likely to react. Retinal burns can cause blind spots and compromise long-term vision. While this damage occurs nearly immediately with the flood of light from looking at the sun, another form of light given off by the star can cause damage to retinal cells with repeated exposure: blue light.

Blue Light and the Sun

Though many refer to digital devices as the main source of blue light throughout the day, the sun is the most powerful source of blue light. With such a sun-centered event, people should be aware of all the possible dangers surrounding the eclipse. Blue light causes a chemical reaction inside of the retina, leading to oxidation that damages the eye, eventually impairing vision. So whereas the immediate effects of the eclipse call for protection, so do the ongoing effects of continuous blue light exposure.

Protect Your Eyes

Protection is paramount to enjoying the solar eclipse. Eclipse viewing glasses will be a necessity for safely viewing this rare occurrence. They can be found through a number of different vendors, but we recommend NASA-approved brands to be sure you're getting the greatest protection. As for blue light, people need a more long-term solution, considering we all encounter this danger every day.

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Sources:

1. Chou, B. Ralph. “Eye Safety During Solar Eclipses.” NASA Eclipse Web Site, NASA, 1 June 2012, eclipse.gsfc.nasa.gov/SEhelp/safety2.html.
2. “Eclipse 2017.” NASA's Eyes, NASA, 17 May 2017, eyes.jpl.nasa.gov/eyes-on-eclipse-web-app.html.
3. “Eclipse: Who? What? Where? When? and How?” Total Eclipse 2017, NASA, eclipse2017.nasa.gov/eclipse-who-what-where-when-and-how
4. “Lunar Eclipses and Solar Eclipses.” NASA Space Place, NASA, 20 June 2017, spaceplace.nasa.gov/eclipses/en/.
5. Pappas, Stephanie. “Can a Solar Eclipse Really Blind You?” LiveScience, Purch, 18 May 2012, www.livescience.com/20433-solar-eclipse-blind.html.