Total solar eclipse on 12 August 2026: how to watch it safely
On 12 August 2026, Spain will witness one of the most spectacular astronomical events of the century: the first total solar eclipse visible from the Iberian Peninsula since 1912. Over a hundred years of waiting for this moment. If you are within the path of totality — which crosses northern Spain from west to east — you will have around 76 seconds to see it at its most magnificent.
But before marking your calendar and preparing your viewing spot, there is something you must know: looking directly at the sun, even during an eclipse, can cause permanent and irreversible damage to the retina. In this article we explain which glasses you need, how to tell certified ones from those that are not, and everything you need to know to experience the eclipse safely.
The greatest astronomical event of the century in Spain
The path of totality will cross Spain from A Coruña to Valencia. Within the totality zone, the sun will disappear for between 60 and 76 seconds. In the rest of the peninsula, the eclipse will be partial but equally spectacular.
Where and when will the eclipse be visible?
The eclipse will begin as a partial eclipse at around 19:30 in the westernmost parts of Spain and will reach its maximum at approximately 20:28. Taking place at sunset, the sun will be low on the horizon, which adds an extraordinary visual dimension — and also some logistical challenge, as you will need a clear western horizon.
Here are some of the provincial capitals within the path of totality:
Cities outside the path of totality — such as Barcelona, Madrid, Seville or Málaga — will see a partial eclipse that is equally impressive, although without the brief seconds of complete darkness.
Why the eclipse is dangerous for your eyes
During an eclipse, we instinctively look at the sun for longer and with greater attention than usual. The problem is that solar radiation — ultraviolet, infrared and high-intensity visible light — literally burns the cells of the retina when exposure is prolonged or without adequate protection.
The damage is called solar retinopathy. The most alarming thing is that it does not hurt at the time: the retina has no pain receptors. The damage appears hours later, with loss of central vision, dark spots or permanent visual distortion. In some cases, it is irreversible.
❌ Regular sunglasses
Even the highest-category UV400 sunglasses (Cat. 4) block only 97% of visible light. The remaining energy is sufficient to damage the retina when looking directly at the sun during the eclipse.
❌ Smoked or darkened glass / improvised filters
Smoked glass, photographic negatives or crisp packet wrappers do not filter infrared radiation or a large proportion of UV. These are popular methods but completely ineffective and dangerous.
❌ Looking through a mobile phone
A mobile phone camera does not protect your eyes either. And zooming in does not help: the same radiation still reaches your retina through the screen.
❌ Welding goggles without certification
Standard welding goggles (DIN 5) do not filter enough solar light. Only DIN 14 or higher are acceptable, but ISO 12312-2 certified glasses are the correct and safe option.
✅ ISO 12312-2 certified eclipse glasses
The only international standard specifically for direct solar observation. They reduce sunlight by more than 100,000 times. They are the only truly safe option for viewing the eclipse.
✅ Indirect projection
Projecting the image of the sun onto paper using a cardboard box or two sheets of card is 100% safe and requires no special materials. Ideal for young children.
Eclipse glasses: what to look for
Not all "eclipse glasses" are the same or safe. The market is flooded with fake or uncertified products with every major eclipse. Here is what you need to check before buying:
12312-2:2015
The only standard that guarantees real safety
The ISO 12312-2:2015 standard is the international standard specifically for direct solar observation filters. Glasses bearing this certification block more than 99.9997% of visible light and all harmful UV and infrared radiation. Make sure the full number is printed, not just "ISO" or "CE".
| What to look for | Why it matters | Verdict |
|---|---|---|
| ISO 12312-2:2015 marking | International standard specifically for direct solar viewing | Essential |
| CE marking | Compliance with European safety regulations | Essential |
| Optical density filter ≥ 5 | Minimum opacity level for safe solar viewing | Required |
| No scratches or holes | Any imperfection in the filter compromises protection | Check before use |
| Standard UV400 sunglasses | Protect against everyday sun but not direct solar observation | Not valid for the eclipse |
| Very low price with no certification | Indicative of the absence of genuine certification | Avoid |
How to watch the eclipse step by step
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1
Get ISO 12312-2 certified glasses
From specialist opticians, astronomy shops or approved distributors. Avoid uncertified versions circulating online without any guarantees.
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2
Inspect the glasses before the day
Check that the filter has no scratches, pinpricks or damaged areas. If the filter is damaged, do not use the glasses even if they carry the certification.
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3
Find a location with a clear western horizon
The 12 August eclipse will occur at sunset, with the sun very low in the sky. You will need an elevated terrace, a hillside or an open space with no buildings to the west.
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4
Put your glasses on BEFORE looking at the sun
Never look first and then put your glasses on. The correct sequence is: glasses on → turn your head towards the sun → observe → look away → remove glasses.
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5
During totality: you may remove your glasses (only within the totality zone)
This is the only moment when looking directly at the sun is safe: when the moon covers it completely (the solar corona is visible). But this is only during the exact seconds of totality, and you must put your glasses back on the instant the first ray of sunlight appears.
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6
For children: strict supervision or indirect projection
Children can react unpredictably and remove their glasses at the wrong moment. A 100% safe alternative is to project the image onto paper using two sheets of card or a cardboard box.
Can people who wear prescription glasses watch the eclipse?
Yes, absolutely. There are several options:
- Eclipse glasses with adjustable arms that fit over regular prescription glasses (over-glasses). These are the most practical solution.
- Solar filters for telescopes or observation that can be combined with your usual vision correction.
- Indirect projection, which requires no direct viewing of the sun at any point and works with or without glasses.
What you should not do is assume that your prescription glasses with anti-UV coating will protect you from the sun during the eclipse. They will not, even if they have the best treatment available on the market.
Frequently asked questions about the eclipse and eye safety
Have questions about how to watch the eclipse safely?
At Òptica Florit we are vision specialists. Consult us before the eclipse about the best options for your situation: prescription glasses, contact lenses, children... We are here to help you enjoy the event of the century without any risks.
Speak to our specialists