Monday, August 14, 2017

Eye Safety and the Total Solar Eclipse

Total Eclipse of 2017
On August 21, 2017 millions of eyes will be looking upwards to catch a glimpse of what is being dubbed "The Great American Solar Eclipse." This eclipse is indeed an exciting event since it has been nearly 100 years since the last time this has happened.! 

Unfortunately, this spectacular celestial event comes with a risk for those who look without preparation. The reason is that the sun's rays can scorch your retina with little or no warning, possibly causing permanent vision damage. So, it is very important to take some precautions if you decide to look at the eclipse. It can't be stressed enough that even short peeks at the sun can cause harm to your eyes and cause solar retinopathy, which is a hole burned in the retina. 

A total solar eclipse happens when the moon completely blocks the sun. The last time an eclipse like this crossed from coast to coast of North America was back in 1918, according to NASA--but that time it only was visible in a portion of the Northwest and western Canada. This time the total eclipse will cut a 70 mile wide swath from Oregon to South Carolina, while the rest of the continent will be dimmed 

Eye Safety Precautions: 
If you're in the path of the total eclipse (see map), the only time you can view the sun with the naked eye is when the moon completely covers it, known as the "totality." This is when the sun's corona (glowing gas aura) become visible. AT ANY OTHER TIME YOU SHOULD VIEW THE ECLIPSE THROUGH SPECIAL GLASSES! Or, if you don't have access to the eclipse glasses, NASA's website  offers instructions how to make homemade  pinhole projector from paper or a cereal box.

Make sure you buy certified eclipse glasses (beware of fakes!). Don't rely on your sunglasses. Normal sunglasses block about about half of the amount of light compared to specially manufactured protective eclipse glasses. They must meet an international standard known as ISO 12312-2--which is marked on the glasses so look for it because the American Astronomical Society has warned that many glasses being sold don't meet that standard even if they say they do so make sure you look for that number or go to the American Astronomical Society's website for a list of sellers that are certified for safety. 

Other Precautions:
Other safety concerns aside from proper glasses: 
* children: keep watch of them during the eclipse since most reported cases of solar retinopathy involve children. 
* don't magnify: don't use a telescope, binoculars or look through a camera unless there is a special solar filter over the lens
*driving: during the eclipse watch for distracted drivers and/or pedestrians. Most importantly, don't attempt to drive wearing the eclipse glasses! 

If you look:
If you're watching the eclipse from the path of totality, you should remove your eclipse glasses during totality.  If you keep your filters on during totality, you won't see anything because they block out almost all light. However, if you're watching the partial solar eclipse from other parts of the U.S., you must keep them on the entire time. If you take them off, not only do you risk burning your eyes, but you also won't be able to see the eclipse.

Have fun but be well informed. The following sites can help you plan for a safe, maybe once-in-a-lifetime event. 

If you don't have time to plan for this eclipse, take heart, here's a planner for the next 30 years. What are you doing in 2024?