On Monday, August 21 the moon will pass between the earth and the sun, turning day into night for a short period of time. The total solar eclipse will happen above parts of our viewing area, but you risk permanent damage to your eyes or possibly blindness down the road if you don't watch the eclipse safely. Here's what you need to know about getting reliable glasses.
At minimum, the reference number ISO 12312-2 (or ISO 12312-2:2015) must be printed on the inside of the glasses. This means they were made using the latest strict international safety guidelines.
However, you can't trust all brands. NASA has recently warned of unsafe glasses being made/distributed by dishonest companies. The agency recommends the following brands as the best in the business: American Paper Optics, Rainbow Symphony, Thousand Oaks Optical, and TSE 17.
To avoid getting your hands on counterfeits, make sure the manufacturer's information AND the ISO code appear on the glasses.
No matter where you buy your glasses inspect the lenses closely. Make sure they're not scratched or wrinkled because this would make them unsafe to wear. Also, don't reuse eclipse glasses if they're more than three years old.
Wearing these glasses during the partial phases of the eclipse is extremely important. These are the times when only some of the sun will be covered by the moon. When the sun is totally covered it's fine to sneak a peak without eye wear, but only for a brief time. As the moon continues to move past the sun it's important to put your glasses back on to avoid permanent eye damage or blindness. Sunglasses are never a substitute for eclipse glasses. However, welder's goggles are acceptable if Shade 12 or higher. Also, eclipse glasses should be worn over top of regular eyeglasses.
The partial eclipse will start around 1 p.m. eastern time, and the total solar eclipse will begin around 2:30. Spring City, TN will be in the center line, meaning people there will get the full two minutes and forty seconds of the total eclipse. People within approximately 50 miles of Spring City will see the total eclipse for as little as little as 30 seconds or as long as two minutes and fifteen seconds.