Dr Mary Gregory, OD of the Year!
NASA’s 2017 Total Solar Eclipse Map (click to enlarge)
Monday, August 21, 2017 is an exciting date for North Americans: on this day, a solar eclipse will be visible to everyone on the continent (weather permitting). This might also be one of the few times your optometrist might encourage you to take a look towards the sun – but only with protection, of course!
For most people across the continent (about 500 million viewers), a partial solar eclipse will be visible for 2 to 3 hours. A lucky few (well, 12 million!) will be able to see the rare and beautiful phenomenon of a total eclipse – but only briefly. Those within a narrow band from Oregon to South Carolina will experience the sun’s complete blockage, which will allow bright stars and even planets to be visible for a short time, as the day turns to night.
Viewing the Eclipse Safely
Here in Minnesota, we will only see a partial eclipse. If you plan on taking a look in the direction of the sun for this event locally or elsewhere, be sure to use caution. Because the upcoming eclipse will be viewable by millions of people across North America, it’s important for us to understand how to view the eclipse safely. Only within the narrow strip of land called the “path of totality” – and only once the sun is completely blocked by the moon – can viewers safely look at the eclipse without protection.
The only completely safe way to look at the eclipse is by using approved solar eclipse viewers. These special filters, often known as “eclipse glasses,” must meet standards to ensure safe viewing. Other viewers, such as sunglasses, telescopes, smoked glass, binoculars, and polarized filters, are not safe.
If these special viewers are not available, you can build your own viewer, often called a pinhole camera or pinhole projector. Luckily, these are very easy to make with common household items. First, cut a one-inch square hole in the middle of a piece of cardstock. Then, tape a piece of aluminum foil over the hole. Once it’s secure, use a pin to poke a small hole in the aluminum foil. To use your projector, place a second piece of cardstock on the ground and hold the piece with aluminum foil above it, with the foil facing up. Stand with your back to the sun and view the projected image on the cardstock below you – the farther away you hold the paper, the bigger the projected image will be.
The Rare Total Eclipse
Total eclipses are rare in that they only occur once each year or every other year. They’re also rare because you need to be in the path of totality to get the exact angle where the moon blocks the sun. Generally, this area is pretty far off the beaten path (like across an ocean or the Sahara desert), so very few people in the world have ever seen a total eclipse.
The last total solar eclipse that was able to be seen in the contiguous United States happened on February 26, 1979. The path of this total eclipse passed through Oregon, Washington, Idaho, Montana, North Dakota, and the Canadian provinces of Saskatchewan, Manitoba, Ontario, and Quebec. After this year, the next total solar eclipse in the U.S. will occur on April 8, 2024, and will be visible from the United States in a band from Texas to Maine.
Total eclipses are almost as short as they are rare: once a total eclipse begins, there is only a minute or two of totality before the sun starts to become visible again.
Be Safe While Making Memories
Ultimately, it’s never a good idea to look towards the sun, as the concentrated rays can harm eyes quickly. If you have discomfort or problems with your vision after the eclipse, visit us for a comprehensive eye exam. If you plan ahead and use caution, however, you can prepare yourself for one of nature’s most beautiful spectacles. Enjoy the view!
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