Watch the eclipse safely

Why looking at the Sun damages your eyes

Looking at the Sun concentrates enough light and infrared energy on the retina to destroy its photoreceptors - this is solar retinopathy. The process is doubly deceptive: the retina has no pain receptors, and symptoms (a dark spot at the centre of vision, distorted lines, reduced acuity) may only appear several hours after exposure. The damage is often permanent.

A partial eclipse increases the risk rather than reducing it. The drop in ambient light suppresses the natural glare reflex that normally prevents anyone from staring at the Sun for more than a fraction of a second. Yet even a 99%-covered Sun remains thousands of times brighter than the full Moon. On 12 August 2026, the eclipse will be partial everywhere in France - so the danger lasts from first to last contact.

ISO 12312-2 eclipse glasses

The international standard ISO 12312-2 defines the only filtration level recognised for direct naked-eye solar viewing: the filter transmits only about one hundred-thousandth of visible light and blocks ultraviolet and infrared. Before buying or reusing glasses:

• check that ISO 12312-2 (or ISO 12312-2:2015) is printed on the frame, with an identifiable manufacturer;
• inspect the filter in bright light: a scratch, pinhole or peeling film makes it unusable;
• test them: through the filter you should see nothing but the Sun itself or a very intense source (a halogen lamp filament);
• wear them over your prescription glasses if needed, never instead of them;
• supervise children constantly - the glasses slip easily on small faces.

They are sold by opticians, planetariums, astronomy clubs and specialist retailers for a few euros. Buy early: during previous eclipses, stocks sold out in the weeks before the event.

Indirect viewing methods

Projection methods are the only ones that require no certified equipment - and the best suited to groups and young children, since nobody looks at the Sun.

The pinhole

Punch a 2-3 mm hole in a piece of card, turn your back to the Sun and let the light pass through the hole onto a second card or the ground: an inverted image of the solar crescent forms there. The greater the distance between the two surfaces, the larger (and fainter) the image. A colander or the foliage of a tree produces the same effect - dozens of small crescents projected on the ground.

Instrument projection

Binoculars or a small telescope can project a magnified image of the Sun onto a white sheet placed behind the eyepiece. Absolute rule: nobody must ever look into the eyepiece, neither while aiming nor while observing. Do not leave the instrument pointed and unattended, and keep sessions to a few minutes to avoid overheating the optics.

Instruments and photography

Any optics that concentrate light - binoculars, telescope, telephoto lens - multiply the danger. The rule is the same for the eye and for the sensor:

• a dedicated solar filter (full-aperture film or glass) always mounts in front of the objective, never between the eyepiece and the eye;
• never combine eclipse glasses with an instrument: the concentrated light burns through the filter within seconds;
• remove or cover the telescope's finder scope;
• with a smartphone, place a filter (or an eclipse-glasses lens) in front of the camera and frame via the screen, never with the naked eye.

The specific case of 12 August 2026

This eclipse happens at the end of the day: at maximum, around 20:15 - 20:30 depending on the city, the Sun will only be a few degrees above the western horizon. A low, reddening Sun looks less aggressive - that is an illusion: as long as any fraction of the disc is visible, unprotected viewing remains dangerous. Check the times and obscuration percentages city by city to plan your observation.

Only one situation allows the naked eye: being inside the path of totality, in Spain or Iceland, during the moments when the Sun is completely hidden. As soon as the first ray reappears, the glasses must go back on immediately.

In case of accidental exposure

If you stared at the Sun without protection, even briefly, see an ophthalmologist without waiting for symptoms. A blurred or dark spot at the centre of vision, washed-out colours or straight lines that look wavy in the following hours or days are signs of solar retinopathy and warrant an urgent fundus examination.