Safety Guide
How to Watch a Solar Eclipse Safely
A total solar eclipse is one of nature's most spectacular events. But looking at the sun without proper protection can permanently damage your eyesight in seconds. This guide covers everything you need to watch safely.
The Golden Rule: Never Look Without ISO Certified Glasses
The sun emits harmful ultraviolet, visible, and infrared radiation at intensities that can cause permanent retinal damage - eclipse retinopathy - in as little as a few seconds of direct exposure. This damage is often painless and may not be immediately apparent.
The only safe way to observe a partial solar eclipse, or any phase of a total eclipse outside of complete totality, is through ISO 12312-2 certified eclipse glasses. These reduce sunlight by a factor of 100,000, bringing it to a safe level for direct observation.
What NOT to use:
- ✗ Regular sunglasses (even very dark ones)
- ✗ Smoked glass or darkened CDs/DVDs
- ✗ Camera filters not rated for solar use
- ✗ Stacked sunglasses
- ✗ Homemade filters of unknown specification
What to Use: ISO 12312-2 Certified Eclipse Glasses
Safe eclipse glasses must carry the ISO 12312-2 international certification. This standard specifies the optical density and transmission requirements for solar filters used for direct observation.
In Europe, look also for the CE mark, which confirms compliance with European safety directives.
Check the certification
ISO 12312-2 must be printed on the frame. If you cannot see this marking, do not use the glasses.
Inspect before use
Check for scratches, holes, or tears. If the lens is damaged in any way, discard the glasses.
Proper fit
Glasses should fit snugly over your prescription glasses if needed. Light should not enter from the sides.
Supervise children
Ensure children keep glasses on throughout the partial phases. Young children should be supervised at all times.
Understanding Totality
During the brief period of complete totality, the moon fully covers the sun's bright disk. During this window only, it is safe to remove eclipse glasses and observe the sun's corona - the ethereal glowing atmosphere visible only during totality.
Critical: Put your eclipse glasses back on immediately as totality ends (at "third contact"). Even a fraction of the sun's disk re-emerging is enough to cause retinal damage.
Important note:
If you are outside the narrow path of totality, the moon never fully covers the sun. Eclipse glasses are required for the entire duration of the eclipse.
Step-by-Step: How to Watch an Eclipse
- 1
Prepare in advance
Order ISO 12312-2 certified eclipse glasses before the event. Stock often runs out in the weeks before a major eclipse.
- 2
Check your glasses
Before eclipse day, inspect your glasses for any damage. Test by holding them up to a bright light indoors - you should see only the light source.
- 3
Find your viewing location
Choose a location with an unobstructed view of the sky. Check the weather forecast and have a backup location.
- 4
Put glasses on before looking up
Never look toward the sun before your eclipse glasses are fully on and secured.
- 5
Observe the partial phases
Through your glasses, watch as the moon takes a larger and larger bite out of the sun.
- 6
Totality (path only)
When the last sliver of sun disappears and totality begins, you may remove glasses and observe the corona. Be ready to replace them the moment totality ends.
- 7
Enjoy and share
After the eclipse, share the experience - eclipse glasses can be given to others or donated to schools for the next eclipse.
Ready to Watch Safely?
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