Eye Safety During a Total Solar Eclipse

Except during the brief total phase of a total solar eclipse, when the Moon completely blocks the Sun’s bright face, it is not safe to look directly at the Sun without specialized eye protection for solar viewing. Viewing any part of the bright Sun through a camera lens, binoculars, or a telescope without a special-purpose solar filter secured over the front of the optics will instantly cause severe eye injury.

During a total solar eclipse, eye safety is crucial because looking directly at the sun can cause serious eye damage or even permanent blindness. Here's how to protect your eyes during the different phases of the eclipse:

1. Before Totality:

• Use Solar Viewing Glasses: During the partial phases of the eclipse, you must use special solar viewing glasses or solar filters. Ordinary sunglasses are not sufficient as they do not block out harmful ultraviolet (UV) and infrared (IR) radiation.
• Ensure Proper Certification: Make sure the solar viewing glasses or filters meet the ISO 12312-2 international safety standard. Avoid using homemade filters or those that are not certified for solar viewing.

2. During Totality:

3. • Safe to View Without Protection: When the moon completely covers the sun and you are in the path of totality, it is safe to look at the eclipse with the naked eye. This phase is known as totality and can last from a few seconds to a few minutes.
   • Prepare for the End of Totality: As the moon begins to uncover the sun, switch back to using solar viewing glasses immediately. The intense sunlight returns very quickly, and you must protect your eyes during this phase.

4. After Totality:

   • Return to Solar Viewing Glasses: Once totality ends and the partial phases resume, continue using your solar viewing glasses or filter until the eclipse has completely finished.

5. Avoid Using Unsafe Methods:

   • No Pinhole Projectors: While pinhole projectors can be safe for viewing the sun indirectly, looking directly through them without proper protection can still be harmful.
   • No Regular Sunglasses: Regular sunglasses, no matter how dark, do not offer adequate protection from the sun’s harmful rays.

6. Special Considerations:

   • Children and Pets: Ensure that children and pets are also protected. They should use solar viewing glasses or stay indoors during the eclipse.

By following these guidelines, you can safely enjoy the awe-inspiring sight of a total solar eclipse without risking your eye health.

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When watching the partial phases of the solar eclipse directly with your eyes, which happens before and after totality, you must look through safe solar viewing glasses (“eclipse glasses”) or a safe handheld solar viewer at all times. Eclipse glasses are NOT regular sunglasses; regular sunglasses, no matter how dark, are not safe for viewing the Sun. Safe solar viewers are thousands of times darker and ought to comply with the ISO 12312-2 international standard. NASA does not approve any particular brand of solar viewers.

Always inspect your eclipse glasses or handheld viewer before use; if torn, scratched, or otherwise damaged, discard the device. Always supervise children using solar viewers.

Do NOT look at the Sun through a camera lens, telescope, binoculars, or any other optical device while wearing eclipse glasses or using a handheld solar viewer — the concentrated solar rays will burn through the filter and cause serious eye injury.

If you don’t have eclipse glasses or a handheld solar viewer, you can use an indirect viewing method, which does not involve looking directly at the Sun. One way is to use a pinhole projector, which has a small opening (for example, a hole punched in an index card) and projects an image of the Sun onto a nearby surface. With the Sun at your back, you can then safely view the projected image. Do NOT look at the Sun through the pinhole!

The circular holes of a colander project crescent shapes onto the ground during the partial phases of a solar eclipse.

Joy Ng

You can make your own eclipse projector using a cardboard box, a white sheet of paper, tape, scissors, and aluminum foil. With the Sun behind you, sunlight will stream through a pinhole punched into aluminum foil taped over a hole in one side of the box. During the partial phases of a solar eclipse, this will project a crescent Sun onto a white sheet of paper taped to the inside of the box. Look into the box through another hole cut into the box to see the projected image.

NASA

Do NOT use eclipse glasses or handheld viewers with cameras, binoculars, or telescopes. Those require different types of solar filters. When viewing the partial phases of the eclipse through cameras, binoculars, or telescopes equipped with proper solar filters, you do not need to wear eclipse glasses. (The solar filters do the same job as the eclipse glasses to protect your eyes.)

A woman looks at the Sun through binoculars that have been fitted with solar filters. Binoculars and telescopes can only be used to look at the Sun when used with solar filters specially designed for that purpose.

NASA/Ryan Milligan

Seek expert advice from an astronomer before using a solar filter with a camera, telescope, binoculars, or any other optical device. Note that solar filters must be attached to the front of any telescope, binoculars, camera lens, or other optics.

A solar filter is attached to the Sun-facing end of a telescope.

Carolyn Slivinski

Here are some important safety guidelines to follow during a total solar eclipse.

You can wear eclipse glasses to safely view the Sun during the partial eclipse phases of a solar eclipse, before and after totality.

NASA/Mamta Patel Nagaraja

• View the Sun through eclipse glasses or a handheld solar viewer during the partial eclipse phases before and after totality.
• You can view the eclipse directly without proper eye protection only when the Moon completely obscures the Sun’s bright face – during the brief and spectacular period known as totality. (You’ll know it’s safe when you can no longer see any part of the Sun through eclipse glasses or a solar viewer.)
• As soon as you see even a little bit of the bright Sun reappear after totality, immediately put your eclipse glasses back on or use a handheld solar viewer to look at the Sun.