Trying to look the Sun in the face is a completely silly challenge. With or without an eclipse, observing the star in direct vision without protection exposes you to enormous risks, including the permanent alteration of sight.
Observing solar eclipses is much riskier than observing lunar eclipses. With each solar eclipse, it is even a real public health issue, because too many careless people look at the star without adequate protection. After the total solar eclipse of August 11, 1999, visible in France, the Institute for Public Health Monitoring identified 147 patients with retinal damage (out of a total of 1,024 consultations organised). In 71% of cases, a decrease in visual acuity was observed, according to the National Syndicate of Ophthalmologists of France (SNOF).
What are the risks of staring straight at the Sun?
” Careless observation of a solar eclipse is likely to cause serious and irreversible ophthalmological damage. “Wrote the Directorate General of Health in January 2015, anticipating a solar eclipse visible on March 20 in France. The risk of burns remains irreversible is real when observing the Sun whether or not there is an eclipse. For those affected, the lesion can result in a scotoma, or the appearance of spots in the visual field.
When observing the Sun without precaution, the risks are of 2 types, according to the SNOF:
- Corneal lesions: painful, they are nevertheless reversible (in several days).
- Retinal lesions: caused by “ the thermal effect of solar radiation and a photochemical effect on particularly fragile retinal cells “. These lesions can be irreversible and permanently alter vision.
The Sun emits a flux of intense light, in the visible range, but especially in the infrared: according to the Paris Observatory, it is above all this light that risks causing irreversible eye damage. The risk is all the greater because our retina is insensitive to pain », Indicates the observatory. In other words, at the time of the burn, we do not realize the trauma inflicted on the retina, which is very fragile. There are no immediate symptoms: It is only a few hours later that clinical signs appear, such as visual disturbances or reduced visual acuity. », indicated the Directorate General of Health in 1999, in prevention of the August eclipse.
Even a very short exposure runs the risk of very serious lesions: as early as one minute after the observation, retinal lesions may already be present. Looking at the Sun intermittently is no less dangerous: This way of proceeding is also dangerous because it leads to an accumulation of successive attacks on the retina leading to the same result as prolonged continuous observation. “, according to the General Directorate of Health.
“By the time you are dazzled it is already too late”
As for the uses of optical instruments, such as binoculars, a telescope or a camera, to look at the Sun, the danger is all the greater: retinal lesions can appear in a fraction of a second. You never put your eye behind an optical instrument that focuses sunlight, insists the Paris Observatory. Forget sunglasses, absolutely not designed to look at the Sun in the face, because they do not protect against infrared radiation. ” By the time you’re dazzled it’s already too late “, adds the observatory.
How to Look at the Sun Safely
To look at the Sun in complete safety, it is therefore necessary to opt for special protective glasses, totally opaque to normal light. The glasses must comply with European Directive 89/686/EEC (the CE conformity marking must be written on the glasses), such as those sold by La Maison de l’astronomie.
If you already have such glasses at home, you can reuse them on two conditions: you must have kept them carefully and that they are no more than a year old. Otherwise, it is better to consider that these glasses are for single use, because the quality of their filter can deteriorate if they are stored in bad conditions (humidity, dust, etc.).
When observing with the glasses, take breaks to rest your eyes. If you don’t have glasses, don’t take any risks and observe the Sun indirectly. You will find in this other article 2 tips for observing a solar eclipse in safety, keeping your back to the Sun.
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