To watch a solar eclipse safely, you need either certified solar viewing glasses that meet the ISO 12312-2 standard or an indirect viewing method like a pinhole projector. The single most important rule: never look at any part of the visible sun without proper filtration, except during the brief moment of totality in a total eclipse when the moon completely blocks the sun’s bright face.
What Happens if You Look Without Protection
Staring at the sun, even during an eclipse when most of the disk is covered, causes a condition called solar retinopathy. The sun’s light concentrates on the back of your eye and causes both thermal and photochemical damage to the cells responsible for your central vision. The thermal component heats retinal tissue by at least 10°C, while blue light triggers a chemical reaction that destroys cells in the layer that supports your photoreceptors. Because the retina has no pain receptors, you won’t feel anything in the moment.
Symptoms typically appear within hours: blurred central vision, blind spots, distorted shapes, light sensitivity, and headache. Most people recover within weeks to six months. A study of 70 cases from the 1999 solar eclipse found that all patients regained full vision within six months, but some cases do result in permanent impairment. The risk simply isn’t worth it when safe viewing is so easy.
Eclipse Glasses and What Makes Them Legit
Proper eclipse glasses are at least 1,000 times darker than the darkest regular sunglasses you can buy. They block nearly all ultraviolet, visible, and infrared light, letting through only a tiny fraction that allows you to see the sun as a bright, sharp disk. The international safety standard governing these filters is ISO 12312-2, first adopted in 2015 and reaffirmed in 2020. It sets strict limits on how much light can pass through at every wavelength that reaches your retina.
The problem is that anyone can print “ISO 12312-2” on a pair of flimsy glasses. To verify yours are genuine, the American Astronomical Society maintains a list of verified manufacturers and vendors. Cross-reference your glasses against that list rather than trusting a random online seller. Also ignore any claim that glasses are “NASA-approved,” since NASA does not endorse commercial products.
If you’re unsure about a pair you already own, try this three-part home test. First, put them on indoors. You should see nothing except very bright light sources like a halogen bulb or a phone flashlight held right up to them. If you can see your surroundings, they’re no good. Second, step outside (without looking at the sun) and confirm you still can’t see anything besides extremely bright reflections. Third, glance briefly at the sun. You should see a comfortable, sharp-edged, round disk. If the glasses pass all three checks, they’re likely safe.
Welding Filters as an Alternative
A welding filter with a shade number of 12 or higher is safe for direct solar viewing. Most people find shade 12 uncomfortably bright and shade 15 too dark, so shade 13 or 14 hits the sweet spot. The view will be green-tinted rather than the yellow-orange you see through eclipse glasses, but the protection is equivalent.
One critical warning: do not use adjustable or auto-darkening welding helmets. Many don’t reach shade 13, and even those that do carry serious risk. You could accidentally bump them to a lighter setting, or the auto-darkening sensor may not react fast enough when you look at the sun.
Build a Pinhole Projector
If you don’t have eclipse glasses, the safest approach is indirect viewing with a pinhole projector. The simplest version requires two pieces of white cardstock. Poke a small, clean hole in one card, hold it up so sunlight passes through the hole, and let the image fall onto the second card held a foot or two behind it. You’ll see a small projection of the sun with the moon’s silhouette crossing it.
A box version works even better. Take a long cardboard box (a cereal box works), cut a small square opening on one end, tape a piece of aluminum foil over it, and poke a tiny hole in the foil with a pin. Tape a white piece of paper inside the opposite end of the box. Point the foil end toward the sun, look into the open end of the box, and the eclipse will be projected onto the white paper. The longer the box, the larger the image. NASA has published multilingual video instructions for this project. You never look at the sun at any point during this process.
When You Can Look Without Glasses
There is exactly one moment when you can safely look at an eclipse with your naked eyes: totality during a total solar eclipse. This is when the moon completely covers the sun’s bright face, leaving only the faint corona visible. You’ll know totality has arrived when you can no longer see any part of the sun through your eclipse glasses. The sky darkens dramatically, and the corona appears as a wispy halo around the black disk of the moon.
Totality lasts anywhere from a few seconds to about four and a half minutes, depending on the eclipse and your location within the path. The instant you see even a sliver of bright sunlight returning at the edge of the moon, put your glasses back on immediately.
This exception applies only to total eclipses. During an annular eclipse (the “ring of fire” type), the moon never fully covers the sun’s disk, so you must keep your solar filter on the entire time. The same goes for partial eclipses.
Protecting Your Phone and Camera
Your phone’s camera sensor can be damaged by the same intense, focused light that harms your eyes. The lens concentrates sunlight onto a tiny sensor that isn’t built to handle it, and even brief direct exposure can burn pixels permanently. If you want to photograph the eclipse with your phone, place a solar filter over the lens, the same type used for telescopes and cameras. Holding your eclipse glasses over the phone lens in a pinch can work for a quick snapshot, but a proper clip-on solar filter gives better results and more reliable protection.
During totality in a total eclipse, you can remove the filter to capture the corona, just as you would remove your glasses to view it with your eyes. Put the filter back on the moment the sun reappears.
Keeping Pets Safe
Dogs, cats, and birds don’t normally stare at the sun. Their natural reflexes keep them from looking directly at it, and an eclipse won’t change that instinct. The bigger concern is the disruption around the event itself. If you’re hosting a viewing party, extra foot traffic means more chances for a pet to slip out an open door. Set up a second barrier like a baby gate or keep your dog on a leash. If your pet gets anxious around crowds or unusual activity, talk to your vet beforehand about calming strategies. And if the sudden midday darkness makes your pet drowsy, just let them nap.
Upcoming Total Solar Eclipses
The next total solar eclipse falls on August 12, 2026, with totality visible from Greenland, Iceland, and Spain (plus a small area of Portugal and parts of Russia). A partial eclipse will be visible across most of Europe, parts of Africa, and portions of North America.
The following year, on August 2, 2027, a total eclipse will cross southern Spain, Morocco, Algeria, Tunisia, Libya, Egypt, Saudi Arabia, and Yemen. A partial eclipse will be visible across most of Europe, much of Africa, the Middle East, and parts of Southeast Asia and eastern Canada. If you’re planning travel for either of these, securing a spot within the narrow path of totality is what makes the difference between a partial dimming and the full experience of the sky going dark.