The total solar eclipse scheduled for August 12 has become one of the most anticipated astronomical events in Spain and much of Europe. Areas such as the Iberian Peninsula, the Balearic Islands, and parts of northern Spain are preparing to experience a few seconds of darkness at sunset, with the solar corona visible to the naked eye… provided the proper precautions are taken.
Ophthalmologists, opticians, and authorities all emphasize the same message: looking at the sun without proper protection is not a game . Direct exposure during an eclipse can cause serious and irreversible eye damage, even if everything feels perfectly normal at the time. Therefore, certified eclipse glasses with solar filters are considered the only safe way to observe the phenomenon directly.
A historic total solar eclipse in Spain and Europe
The eclipse on August 12 will be, in many parts of the Iberian Peninsula, the first total eclipse visible in over a century . The Moon will align with the Sun and Earth in such a way that it will completely block sunlight for a few moments, transforming the landscape and revealing the delicate solar corona.
Across much of Spain, the peak of the phenomenon will coincide with sunset , adding an even more striking visual element. In places like Benavente, for example, the totality phase is expected to last around a minute and a half, one of the longest in the country, while in other areas, such as much of Álava, totality will only last about 30 seconds.
In the Balearic archipelago, the eclipse will also be visible throughout the territory, with peak viewing times around 20:30 p.m. Regional authorities are already working with island councils, emergency services, and security forces to manage travel, potential crowds, and outreach activities related to the event.
Beyond the spectacle, the eclipse is shaping up to be an opportunity for scientific outreach and citizen participation , with inclusive initiatives that seek to allow people with visual disabilities to "experience" the phenomenon through tools that convert the variation of light into sound.
Why you can't look at the eclipse without certified glasses
Experts are adamant: never look directly at the sun , not even when it's partially obscured by the moon. The problem is that, even though the sun's disk may appear less intense, the radiation it emits remains just as dangerous for eye tissue.
The main injury associated with this type of exposure is solar retinopathy . It occurs when radiation damages the photoreceptors in the retina, especially in the macula, the area responsible for detailed central vision. The most worrying aspect is that the damage can be permanent and often doesn't appear immediately.
According to ophthalmologists like Sergio Eguiza, from the Clinical and Surgical Institute of Ophthalmology (ICQO), many people come to the clinic days after the eclipse with central spots in their visual field , blurred or distorted vision, flashes of light, and difficulty reading or recognizing details. In some cases, these alterations do not resolve and leave irreversible damage.
Another factor that increases the risk is a false sense of security. Seeing the sun partially obscured, some people think they can "handle" the light better and maintain eye contact for longer than normal. However, ultraviolet and infrared radiation continues to reach the retina with sufficient intensity to cause burns, even if the observer doesn't feel pain at the time.
Studies conducted after recent eclipses in other countries have detected a significant increase in visits to ophthalmologists due to the use of inadequate eye protection or simply from viewing the phenomenon without any filter. Some sources indicate that calls increased a hundredfold in certain contexts after major eclipses.
Features of approved glasses for viewing a total solar eclipse
To observe the eclipse directly, not just any dark glasses or tinted glass will do. It is essential to use specific eclipse glasses that meet a series of very specific technical requirements and are manufactured with certified solar filters.
Experts recommend always checking that the glasses bear the ISO 12312-2 standard reference and the CE marking. This code indicates that the product has been designed and tested for direct observation of the sun, blocking harmful radiation within the limits required by international standards.
These types of glasses typically incorporate three levels of complementary protection : a filter that blocks around 97% of infrared radiation, another that eliminates approximately 97% of ultraviolet radiation, and an additional layer that reduces around 99,99% of visible light. The result is that the sun is perceived only as a very faint, small disk against a black background.
Thanks to these filters, certified sunglasses allow you to view the sun without dangerous levels of radiation reaching your retina. It's important, however, to check for scratches, cracks, or other damage , and to discard any damaged pairs, as even a small defect can let in more light than necessary.
Another advantage is that many of these glasses can be worn directly over regular prescription glasses , making it easier for people with vision problems to enjoy the eclipse without sacrificing clarity. For children, it's recommended to pay close attention to the fit to prevent them from accidentally removing or shifting the glasses while looking at the sky.
How to choose and use eclipse glasses correctly
When buying eclipse glasses, it's important to pay attention to several details. First, check that the ISO 12312-2 reference and the CE marking are clearly displayed on the product itself or its packaging. If this information is missing or unclear, it's best not to use them to look at the sun.
It is also advisable to purchase them through trusted channels , such as opticians, recognized astronomical associations, scientific institutions, or official distribution programs organized by public administrations. Informal sales without guarantees can lead to counterfeit products or items that mimic the appearance of certified glasses but lack adequate protection.
Once you have them in hand, check that the filters have no holes, scratches, or translucent areas when held up to the light. Any visible defect is reason enough to discard them. Before the day of the eclipse, you can do a quick test by looking at a very bright artificial light: with proper eclipse glasses, that light should appear extremely faint.
Regarding usage, experts recommend putting on the eclipse glasses before looking at the Sun and keeping them on at all times during the partial phases. Only in areas where the eclipse is total, and only during the very brief interval when the Sun is completely covered, is it safe to remove them. As soon as the smallest sliver of light reappears, they should be put back on immediately.
Furthermore, it is strongly advised not to look at the eclipse continuously for its entire duration, even with certified eclipse glasses. The most sensible approach is to take regular breaks , alternating periods of observation with rest periods, especially for children, the elderly, or those with pre-existing eye conditions.
What you should never do when observing a solar eclipse
If there's one thing all the experts emphasize, it's that there are no shortcuts . Conventional sunglasses, no matter how dark or expensive they are, are useless for looking directly at the sun. Neither are tinted windows, makeshift filters made from X-ray film, blackened plastic, or similar items.
In the case of binoculars, telescopes, or cameras, the risk is multiplied. These devices concentrate light and can cause an instant retinal burn if used without specific professional solar filters . Even placing eclipse glasses in front of the lens is not a safe solution, as they are not designed to handle the intensity of light collected by an optical instrument.
Another false solution is to be complacent because the day is cloudy or the sun is visible through a light layer of clouds. Although the apparent brightness decreases, harmful radiation still penetrates the atmosphere , so the need for eye protection does not disappear if you are going to look at the sun.
Alternatively, for those who do not have certified eclipse glasses or prefer not to look directly at the sun, indirect methods such as pinhole camera projection are recommended (a simple box with a small hole that projects the image of the sun onto a surface). This way, the eclipse's progression can be followed without exposing the eyes to radiation.
In any case, if after the event symptoms such as blurred vision, spots in the center of the visual field, flashes of light, distortion of straight lines or difficulty focusing appear, professionals insist that it is essential to go immediately to a specialist for a complete check-up.
Additional recommendations and preparation in different regions
Several regional and local authorities have already begun issuing specific recommendations for the eclipse. In popular tourist destinations, such as the Balearic Islands , coordination plans have been activated with island councils, civil protection, security forces, and health services to manage the increased travel to the best viewing locations.
Measures are planned such as temporary road closures in particularly busy areas, reinforcements of public transport, the creation of open spaces with good visibility of the western horizon, and information points where basic questions about eye safety and the times of the phenomenon can be answered.
Authorities also emphasize aspects that are not strictly visual but equally important: staying well hydrated in the middle of August, protecting the skin with sunscreen, avoiding prolonged exposure to heat, and taking extra precautions in forest or coastal areas to reduce the risk of fires and accidents.
In northern Spain, such as Álava , and in areas of the northwest, astronomical associations and local media recommend carefully choosing an observation site, prioritizing locations with a clear western horizon and avoiding areas where evening fog is common in summer. They also remind people that, although the total phase lasts only seconds, the complete eclipse extends for approximately two hours from the first contact to the last.
Furthermore, scientific institutions such as the CSIC are promoting projects that allow people with visual impairments to follow the eclipse using devices that transform light variations into sound, creating a kind of "sound map" of the phenomenon. These devices are distributed free of charge to event organizers, with the aim of fostering inclusive activities in different parts of the country.
Adding together medical recommendations, safety warnings, and public awareness campaigns, the total solar eclipse of August 12th is shaping up to be an exceptional event in Spain and Europe, provided one basic rule is followed: protect your eyes with approved eclipse glasses and certified filters at all times when looking at the sun. In this way, the experience can be fully enjoyed without jeopardizing long-term vision.