On August 21, 2017, the entire United State will see a partial eclipse of the sun. Parts of 11 states will experience a total eclipse. It is important to be very careful when watching a total eclipse to prevent inadvertent damage to your eyes. Looking directly at the sun during most parts of the eclipse can permanently damage your vision of blind you! However, there are methods available to view a solar eclipse safely.
The area of the earth in the United States that will be in the path of the total eclipse is only 70 miles wide and will move across the United States relatively rapidly. Plan now where you want to be to observe the eclipse and be sure to have a back up plan in case bad weather for eclipse viewing is predicted.
The only time it is safe to look directly at the sun is when it is completely covered by the moon during the totality phase of an eclipse. At all other times, you must protect your eyes or you could damage your retina possibly causing blindness. Areas outside of the path of the total eclipse will have a partial eclipse. Only part of the sun is blocked even at the peak of the eclipse. In those areas, there is NO SAFE TIME to look at the sun with the naked eye. You must protect your eyes while watching the entire eclipse.
Don’t let these warnings frighten you as there are safe ways to watch the eclipse. 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 standard worldwide known as ISO 12312-2. Keep in mind ordinary sunglasses, even very dark ones, or homemade filters are NOT SAFE for looking at the sun.
Steps to follow for safely watching a solar eclipse:
- Carefully look at your solar filter or eclipse glasses before using them. If you see any scratches or damage, do not use them.
- Always read and follow all directions that come with the solar filter or eclipse glasses. Help children to be sure they use handheld solar viewers and eclipse glasses correctly.
- 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 expert astronomer if you want to use a special solar filter with a camera, a telescope, binoculars or any other optical device.
Another way to watch the eclipse safely is to do so indirectly through a pinhole viewer or video display. A pinhole viewer lets you project an image of the sun onto another surface, like paper, a wall, or pavement. Also NASA will have a live stream of the eclipse that will be safe to watch. Consider watching online, at a local planetarium, science center or club where the appropriate safety measures have been taken.