On August 21, 2017 people across the United States will witness a solar eclipse. Anyone within the path of totality, which stretches from Salem, Oregon to Charleston, South Carolina will be able to observe the moon completely covering the sun. The sun’s tenuous atmosphere, the corona, can also be observed. Those outside this path will still see a partial solar eclipse where the moon covers part of the sun’s disk. If you are wishing to catch a glimpse of this rare astronomical phenomenon, be sure to do so in a way that protects your eyes. Read on for everything you should know when viewing a solar eclipse.
Why is it Dangerous?
During a solar eclipse, the only time that it is 100% safe to look at the sun is when a total eclipse occurs, and the moon completely blocks out the sun. Solar eclipses are dangerous because the sun can come out from behind the moon and “surprise you” before you have a chance to look away. Looking directly at the sun during a solar eclipse is more dangerous than on a sunny day because during the total eclipse period, your pupil dilates to let in more light. Then, when the sun reappears and starts flooding the area with light, not only are you staring straight at it, but your eyes are in a state where it is wide open, and actively trying to let in as much light as possible.
There is only one safe way to look directly at the sun, whether during an eclipse or not: through special-purpose solar filters. These solar filters are used in “eclipse glasses” or in hand-held solar viewers. They must meet a very specific worldwide standard known as ISO 12312-2. It is important to remember that sunglasses, even very dark ones, do not offer enough protection for viewing a solar eclipse.
Take the following precautions to keep your eyes safe:
- Inspect your solar filter or eclipse glasses before using them. Do not use them if they are scratched or damaged.
- Always read and follow all directions that come with the solar filter or eclipse glasses. To ensure children use the lenses correctly, monitor them closely.
- Before looking up at the bright sun, stand still and cover your eyes with your eclipse glasses or solar viewer. After glancing at the sun, turn away and remove your filter—do not remove it while looking at the sun.
- The only time that you can look at the sun without a solar viewer is during a total eclipse. When the moon completely covers the sun’s bright face and it suddenly gets dark, you can remove your solar filter to watch this unique experience. Then, as soon as the bright sun begins to reappear very slightly, immediately use your solar viewer again to watch the remaining partial phase of the eclipse.
- Never look at the uneclipsed or partially eclipsed sun through an unfiltered camera, telescope, binoculars or other similar devices. This is important even if you are wearing eclipse glasses or holding a solar viewer at the same time. The intense solar rays coming through these devices will damage the solar filter and your eyes.
- Talk with an astronomer if you want to use a special solar filter with a camera, a telescope, binoculars or any other optical device.
Other Viewing Methods
Solar eclipses can also be viewed through a pinhole projection. NASA has instructions available to make your own.
NASA will be live streaming the event on August 21, which will allow those outside of the total eclipse area to view.
Find an event at a local planetarium or science club to view with others.
The last solar eclipse with a path of totality (area where a full eclipse could be seen) was in March, 2016 in Indonesia and some small islands in Micronesia. After the Aug. 2017 eclipse across North America, the next total solar eclipse will be in South America on July 2, 2019. You don’t want to miss this exciting opportunity! To check how much of the eclipse will be visible in your area, visit this interactive map.