The only safe way to look directly at a solar eclipse is through specially designed solar filters, such as eclipse glasses or handheld solar viewers that meet the ISO 12312-2 international standard. Regular sunglasses, even very dark ones, do not block nearly enough light. Without proper protection, even a few seconds of staring at the sun can cause permanent damage to your retina.
Why Unprotected Viewing Is Dangerous
Your retina has no pain receptors, so you won’t feel anything while the damage is happening. When sunlight enters the eye, it gets focused onto the macula, the small area at the center of your retina responsible for sharp, detailed vision. That concentrated light triggers a combination of photochemical and thermal injury to the photoreceptor cells and the pigment layer behind them.
The photochemical component is driven primarily by blue light, which causes a chain reaction that breaks down fats and proteins in retinal cells. Heat absorption adds to the injury, though studies have shown that the temperature rise from sungazing alone isn’t enough to cook the tissue the way a laser would. Instead, the heat amplifies the chemical damage already underway. The result is solar retinopathy: a blind spot or distorted area in the center of your vision that can appear hours after exposure and may be permanent.
Symptoms typically include blurred central vision, a dark or bright spot that won’t go away, distorted shapes, or changes in color perception. These can show up within hours of exposure. Some people recover partially over weeks or months, but others are left with lasting impairment that affects reading, driving, and recognizing faces.
Eclipse Glasses and Solar Viewers
Certified eclipse glasses block all but a tiny fraction of sunlight. The ISO 12312-2 standard requires that they transmit no more than 0.0032% of visible light, which is equivalent to a shade 12 welding filter at minimum. Most quality eclipse glasses fall somewhere between shade 12 and shade 15 levels of darkness. The standard also caps ultraviolet transmission at or below the visible light level and limits infrared transmission to no more than 3%.
When you put on a legitimate pair of eclipse glasses, you should see nothing at all except the sun itself (or a very bright light source). If you can see your surroundings, the room, the street, or your hand in front of your face, the glasses are not dark enough.
Before using eclipse glasses, inspect them. If the filter material is scratched, punctured, or peeling away from the frame, throw them out. Glasses that are more than three years old or that were used during a previous eclipse may have degraded and should be replaced.
Where to Buy Glasses You Can Trust
The American Astronomical Society maintains a list of vetted manufacturers and sellers whose products have been tested and confirmed to meet ISO 12312-2 requirements. This is the safest starting point. The AAS specifically warns against searching for eclipse glasses on Amazon, eBay, Temu, or other online marketplaces and simply buying the cheapest option. Counterfeit glasses that look identical to certified ones have flooded these platforms before past eclipses.
Before purchasing online, verify that the seller is identified by name on the site and appears on the AAS list. Legitimate glasses will be labeled with the ISO 12312-2 standard number and the manufacturer’s name, but since counterfeiters can print anything on a label, the source you buy from matters more than what’s printed on the frame.
Welding Filters as an Alternative
A shade 14 welding filter is the only welding glass dark enough for safe solar viewing. Shade 12 or 13 filters, while very dark, let through more light than recommended for extended viewing. Shade 14 filters are uncommon in most hardware stores since they’re darker than what most welding applications require, but they can be ordered from safety equipment suppliers. If you already own a welding helmet, check the shade number printed on the filter before using it.
Protecting Cameras, Binoculars, and Telescopes
Binoculars, telescopes, and camera lenses concentrate sunlight the same way your eye’s own lens does, only far more intensely. Looking through any of these devices at the sun without a proper solar filter will cause immediate, severe eye damage. Eclipse glasses worn over your eyes are not sufficient protection when using magnifying optics.
The solar filter must be attached to the front of the device, covering the large objective lens that faces the sky. This blocks the light and heat before they enter the optical system. Never use a filter that threads into the eyepiece at the back end of a telescope. Sunlight focused by the optics ahead of the eyepiece will burn through a rear-mounted filter in seconds. The AAS repeats this point emphatically: the filter goes on the front, always.
Pinhole Projectors for Indirect Viewing
If you don’t have eclipse glasses, a pinhole projector lets you watch the eclipse indirectly by projecting an image of the sun onto a surface. You never look at the sun itself.
You can build one from a cereal box in about ten minutes. Cut a piece of white paper to fit inside the bottom of the box and tape it flat as your projection screen. Seal the top of the box, then cut two small openings at the top. Cover one opening completely with a double layer of aluminum foil and poke a single hole through the foil using a small nail (roughly 3 mm across). Leave the other opening uncovered so you can peer inside the box. With your back to the sun, hold the box up so sunlight enters through the pinhole. You’ll see a small, bright image of the sun projected onto the white paper at the bottom. During the eclipse, you’ll watch the moon’s shadow creep across that tiny disc.
You can also skip the box entirely. A kitchen colander held up to the sunlight will project dozens of tiny crescent suns onto the ground during a partial eclipse. Tree leaves do the same thing naturally, casting crescent-shaped light patterns through the small gaps between them.
Watching With Kids
Children’s eyes transmit more light to the retina than adult eyes, making them more vulnerable to solar damage. Young children also tend to be less reliable about keeping glasses on. For toddlers and infants, indirect viewing methods like pinhole projectors are the safest option. For older children, make sure their eclipse glasses fit snugly and practice using them before the event. Supervise them directly during the eclipse to ensure they don’t lift or remove the glasses while looking up.
The One Exception: Totality
If you are within the path of a total solar eclipse, there is one brief window when you can look at the sun with your bare eyes. During totality, when the moon completely covers the sun’s bright face, the corona (the sun’s outer atmosphere) becomes visible as a glowing ring. This is the only moment when it is safe to remove your eclipse glasses.
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 temperature drops. Totality lasts anywhere from a few seconds to a few minutes depending on your location and the specific eclipse. The instant you see even a sliver of bright sunlight returning at the moon’s edge, put your glasses back on immediately. That first flash of re-emerging sunlight is just as dangerous as staring at the uneclipsed sun.
This exception applies only to total eclipses. During a partial or annular eclipse, some portion of the sun’s surface remains visible at all times, and you need eye protection throughout.
The Next Major Eclipse
The next total solar eclipse falls on August 12, 2026. The path of totality will cross Greenland, Iceland, and Spain, with a small area of Portugal also in the path. A partial eclipse will be visible across most of Europe, parts of Africa, and portions of North America. If you’re planning to travel for it, securing certified solar viewers well in advance is worth the effort. Supplies tend to sell out or become unreliable as the date approaches.