How do I watch a solar eclipse safely?
Never look at the Sun without a solar filter
Except during the brief total phase of a total eclipse, looking at the Sun, even when most of it is covered, can burn the retina. It does not hurt while it happens. Here is how to watch safely, following the American Astronomical Society's Solar Eclipse Task Force.
The rules
- Use proper eclipse glasses or a handheld solar viewer that meets the ISO 12312-2 international standard, bought from a supplier on the AAS list of reputable vendors. Sunglasses, smoked glass and exposed film are not safe.
- Check them before use. Discard glasses that are scratched, punctured or torn. Children should be supervised.
- Put them on before you look up, and look away before you take them off.
- Never look through a camera, binoculars or a telescope while wearing eclipse glasses. The concentrated light burns straight through the filter. Optics need their own certified solar filter mounted on the front (sky) end.
- Totality is the one exception. Inside the path of a total eclipse, once the Moon covers the Sun completely, take your glasses off and look: it is safe and it is the whole point. Put them back on as soon as the bright Sun reappears. An annular eclipse never reaches this point.
No glasses? Project it
A pinhole projector (a small hole in card, with your back to the Sun) casts an image of the crescent Sun onto a second card or the ground. The gaps between leaves in a tree, a colander or crossed fingers do the same. Never look at the Sun through the pinhole.
Lunar eclipses
A lunar eclipse needs no protection at all: the Moon is only reflecting dimmed sunlight.
Source: American Astronomical Society, Solar Eclipse Task Force: Eclipse Eye Safety. This page is general guidance, not medical advice. If your eyes hurt or your sight changes after looking at the Sun, see an eye doctor.
Questions
Can I look at a solar eclipse with sunglasses?
No. Even very dark sunglasses let through far more sunlight than is safe. Use eclipse glasses or a handheld solar viewer that meets the ISO 12312-2 standard.
When is it safe to look without glasses?
Only during totality of a total solar eclipse, when the Sun is completely covered, and only inside the path of totality. Look away or put your glasses back on as soon as the Sun starts to reappear. During a partial or annular eclipse, it is never safe.
How do I know my eclipse glasses are safe?
Buy from a supplier on the American Astronomical Society's list of reputable vendors. The ISO 12312-2 label alone is not proof, because fake glasses copy it. Do not use glasses that are scratched, torn or older than the maker allows.
Can I use my phone or camera?
Not through eclipse glasses held in front of the lens, and never with binoculars or a telescope: they concentrate the light and need a solar filter mounted on the front. A phone camera pointed at the Sun can be damaged; it is your eyes that matter most, so look at the screen, not the Sun.
What about a lunar eclipse?
A lunar eclipse is completely safe to watch with your eyes, binoculars or a telescope.