Total Solar Eclipse

Total Solar Eclipse

A total solar eclipse is an exciting phenomenon for amateur astronomers and, as many of you know, the next one will occur on August 21, 2017. In a total solar eclipse, the moon completely covers the sun for a brief period of time and the sky becomes dark. The corona, or the sun’s outer atmosphere, will gradually appear, and stars and even planets can be seen. For this upcoming eclipse, there is a narrow band of land that stretches approximately 113 kilometers from the Pacific coast of Oregon to the Atlantic coast of South Carolina where a total solar eclipse will occur. The last coast-to-coast total solar eclipse in the US was recorded on June 8, 1918. Calgary, however, will be experiencing a 77% solar eclipse between the hours of 10:00am to 12:30pm.

There are a few safety measures that need to be considered to experience a solar eclipse safely. Staring into the sun without appropriate eye protection, even for a brief moment, can permanently damage the retina, or the light-sensitive tissue that lines the back of the eye. Wearing a dark pair of sunglasses is just not enough. Additionally, infrared radiation can burn the lens and cornea of the eye.

The only safe way to view the eclipse is through special eclipse lenses that meet a safety standard known as ISO 12312-2. Further to that, the only time that one can view the eclipse without eclipse glasses is during the short period of the total eclipse, a phenomenon that won’t occur here in Calgary since we are expected to see a 77% eclipse. The American Academy of Ophthalmology has posted some more information here:

https://www.aao.org/eye-health/tips-prevention/solar-eclipse-eye-safety

Another way to view the eclipse is to make a simple pinhole camera. Click here to find out how:

https://www.timeanddate.com/eclipse/make-pinhole-projector.html

Additionally, the US NASA site describes an alternative way to safely and indirectly view the eclipse here:

https://eclipse2017.nasa.gov/safety

If you haven’t been able to access appropriate eclipse glasses, there are a few places in Calgary where you can join in the fun with your family. One location isthe University of Calgary and another is the TelusSpark Science Centre. To find out more, head to the links below:

http://www.ucalgary.ca/rao/event/2017-08-21/solar-eclipse-2017
http://www.sparkscience.ca/experience-telus-spark/events/eclipse-party/

Martin Lee OD, PhD
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