Solar Eclipse of 12 August 2026: How to Protect Your Eyes

On Wednesday 12 August 2026, the Moon will begin to bite into the solar disc at around 7:20 PM. The eclipse will reach its maximum at around 8:15 PM, when the Moon will cover nearly 90% of the Sun. The Sun will then set while still partially eclipsed.

The phenomenon will therefore unfold with the Sun already low on the horizon. To observe it well, you will need a clear view towards the west and north-west: a high point, a large square, a field or a terrace facing the right direction.

Observing it is perfectly possible, provided you follow one simple rule. You must put your eclipse glasses on before turning your gaze towards the Sun, and look away completely before taking them off. This rule remains valid for the whole duration of the eclipse.

A solar eclipse occurs when the Moon passes between the Earth and the Sun. The Moon is around 400 times smaller than the Sun, but it is also around 400 times closer to us. Seen from Earth, its apparent size is therefore very close to that of the Sun. In certain circumstances, it can cover part of the solar disc or, from certain regions of the world, almost all of it.

The Moon's shadow cast on the Earth is narrow. People located within this band can observe a total eclipse. Outside this band, the Moon covers only part of the Sun and the eclipse is described as partial.

This is what will happen in Belgium on 12 August 2026. The band of totality will cross Iceland and northern Spain, among other places. Here, the eclipse will remain partial, with a maximum coverage close to 90%.

The part of the Sun that remains visible is still the Sun. When 90% of the disc is covered, the remaining 10% keeps exactly the same light intensity. The luminance of the solar photosphere does not decrease.

The phenomenon is even misleading. The surroundings grow darker, the light seems less harsh and the temptation to look directly at the Sun increases. The danger, however, remains just as real.

The optical media of the eye concentrate sunlight onto a tiny area of the retina. When we stare at the Sun, its image forms on the macula, and more precisely on the fovea, the region responsible for fine vision, reading and detail recognition.

The American Astronomical Society makes this clear: outside a zone of totality, there is no moment during a partial eclipse when the Sun can be looked at directly without a suitable solar filter.

For the eclipse of 12 August 2026, the question does not even arise: there will be no totality in Belgium. Glasses are therefore necessary every time you point your eyes towards the Sun.

The confusion often comes from images of total eclipses. During the phase of totality, the solar photosphere is entirely hidden by the Moon, and the corona, far less bright, becomes visible to the naked eye. This situation will not apply to Belgium.

Turning this exception into a rule for the general public creates a real practical problem. How can you know with certainty the instant when the last fragment of photosphere disappears, and above all anticipate the moment it will reappear? If you wait to see the first sunlight before putting your glasses back on, that light has already reached your retina.

A very brief glance does not automatically cause an injury. Toxicity depends on light intensity and exposure duration. But waiting to perceive the light before protecting yourself is a poor prevention strategy. A single rule is far safer, and it comes down to two actions.

People often speak of a “burn on the retina”. The image is vivid, but it describes the actual mechanism poorly. In solar retinopathy, current evidence indicates that phototoxicity, particularly photochemical phototoxicity, plays the main role. Concentrated light triggers photo-oxidative reactions that damage the cells of the retinal pigment epithelium and the photoreceptors.

The area most affected is the fovea, since it is precisely where the image of the Sun forms when we stare at it.

On macular OCT, abnormalities are seen in the outer layers of the retina, with damage to the ellipsoid zone and other structures corresponding to the photoreceptors.

This condition has several names: solar retinopathy, solar maculopathy, photic retinopathy, or eclipse retinopathy when it occurs after observing an eclipse. These are not different diseases. These names all describe the same phototoxic retinal lesion, caused by staring at a light source that is too intense.

This is one of the most misleading aspects of solar retinopathy. Unlike the cornea or the skin, the retina has no pain receptors. A retinal injury can therefore develop without any unpleasant sensation at the time of exposure.

The absence of pain therefore absolutely does not mean that the observation is safe. Symptoms generally appear in the hours following exposure, sometimes the next day. The damage often affects both eyes, sometimes asymmetrically.

Recovery is common, at least partial recovery. Many patients regain good visual acuity in the weeks or months following exposure.

Regaining visual acuity does not, however, mean a complete return to the previous state. Some people are left with a small central scotoma, distorted images, difficulty reading or reduced visual quality. Photoreceptor abnormalities can remain visible on OCT even when the measured acuity has returned to normal.

The cases documented after the April 2024 eclipse in North America illustrate this well: structural lesions persisted on OCT several months after exposure, despite relatively preserved visual acuity.

No treatment has reliably demonstrated the ability to repair damaged photoreceptors. Prevention therefore remains essential.

You must use glasses specially designed for direct observation of the Sun and compliant with the international ISO 12312-2 standard.

A useful clarification: the phrase “ISO-certified glasses” is misleading. ISO publishes the standard but does not itself certify any product. The mere mention “ISO 12312-2” printed on a frame is therefore not a guarantee, since any manufacturer can print it. The American Astronomical Society recommends buying glasses from manufacturers and suppliers whose products have actually been tested, and publishes a list of vetted vendors.

Before observing, check the condition of the filter. Do not use glasses whose filter is scratched, punctured, torn, coming away from the frame or visibly damaged.

Compliant glasses that have been well kept can, however, be reused. The old advice requiring them to be discarded after three years, or limiting each observation to three minutes, is now considered outdated for modern, compliant filters in good condition.

Ordinary sunglasses are never sufficient, even very dark ones, even category 4. They are designed for looking at surroundings lit by the Sun, not for staring at its photosphere. A compliant eclipse filter transmits around 100,000 times less light than an ordinary sunglass lens.

Nor should you improvise a filter from a material that “seems” dark. X-ray film, a CD, smoked glass or an emergency blanket block visible light by an unknown amount and often let infrared through.

A word on welding masks: certain fixed filters with a very high shade number technically reach an attenuation compatible with solar observation. Adjustable masks or auto-darkening masks, however, are not suitable, since their shade may be insufficient or poorly set. For the general public, compliant eclipse glasses remain the simplest and safest solution.

With a magnifying instrument, the danger increases further. Binoculars or a telescope concentrate sunlight towards the eye.

Wearing eclipse glasses behind binoculars or behind a telescope does not constitute protection. The concentrated radiation can destroy the filter within seconds and expose the eye to a considerable amount of light energy. NASA warns that looking at the Sun through a camera, binoculars or a telescope without a specialised solar filter placed at the front of the instrument can cause severe eye injury.

A filter intended for an instrument must be specifically designed for solar observation, placed in front of the lens, before light enters the instrument, and securely attached.

The ISO 12312-2 standard mainly covers non-magnifying viewers used directly in front of the eyes. It is not a universal certification for telescope or telephoto lens filters.

There is a very simple method for observing the eclipse without ever pointing your eyes towards the Sun: pinhole projection.

Take a piece of card and pierce a small hole in it. Stand with your back to the Sun and let the light pass through the hole and project onto a sheet of white paper or the ground. A small image of the solar disc appears. During the eclipse, this image gradually takes the shape of a crescent.

You must obviously never look at the Sun through the hole. The hole is not a filter, it is only used to project an image.

The phenomenon can even be observed without any equipment at all, under a tree or through a kitchen colander, which works on exactly the same principle.

With children, the rule must be even stricter. A child naturally wants to take the glasses off to “see if it looks different”, or to shift them in front of their eyes. They must therefore be directly supervised throughout the whole observation.

Before letting a child look at the eclipse, put the glasses on them, check that they cover both eyes properly, and only then ask them to turn their head towards the Sun. If they want to take the glasses off, first have them look down or look away.

For young children, pinhole projection is often the simplest and most fun solution.

An accidental glance does not automatically cause solar retinopathy. But you must not, above all, “check” by looking at the Sun again.

Instead, check your vision away from the Sun. Compare the two eyes separately, covering one eye then the other, in front of a piece of text or a grid of regular lines.

If a visual symptom appears and persists after exposure, do not simply monitor it for several days: see a doctor promptly. An examination with an ophthalmologist within 24 to 48 hours makes it possible to rule out another cause and to document the lesion on OCT, which becomes harder later on.

The signs that should prompt a consultation are a persistent decrease in vision, a central spot, a patch of text that disappears, distorted lines, a new difference between the two eyes, or an unusual perception of colours.

The fundus can appear almost normal, especially in mild or early forms. Macular OCT, however, shows the outer retinal layers and the affected photoreceptors very precisely.

The solar eclipse of 12 August 2026 will be one of the most spectacular astronomical events visible from Belgium in many years. It is not dangerous if it is observed correctly.

The difficulty arises when you multiply exceptions, supposedly acceptable durations and complicated rules. One rule alone is enough: glasses on before raising your eyes, gaze turned away before taking them off.

In Belgium, the eclipse will remain partial from start to finish. There will therefore never be a moment when there is a reason to look at the Sun without a filter. With compliant eclipse glasses or pinhole projection, you can fully enjoy the spectacle, without turning an exceptional astronomical event into an eye injury.