solar eclipse august safety precautions

Solar eclipse in August: safety precautions you need to know

Safety warning ahead of solar eclipse on 12 August

The Canary Islands Astrophysics Institute (IAC) has reminded the public of the need to take extreme precautions when observing the upcoming solar eclipse on 12 August, a phenomenon visible across a large part of Spain that is expected to generate widespread public interest. The scientific body has warned that looking directly at the Sun, even during an eclipse, can cause serious and irreversible damage to eyesight, including blindness. For this reason, it insists that the safest method for following the event is to project the Sun’s image onto a surface, rather than looking at it directly.

According to the institute, even as little as one per cent of the Sun’s visible surface emits enough radiation to cause permanent injury to the eye’s light receptors. The eclipse will be a remarkable opportunity to observe one of the most striking astronomical spectacles, but it can also become a risk if inappropriate methods are used.

Government launches official website for eclipse trio

The Spanish government has launched the official website ‘Trio of Eclipses’ to provide information on the solar eclipses of 2026, 2027 and 2028, an exceptional sequence that will have Spain as one of its main viewing locations.

Why looking at the Sun is so dangerous

One of the main dangers of direct exposure to sunlight is that the damage is not always immediately noticeable. Symptoms of solar retinopathy, the eye injury caused by looking at the Sun, can appear hours or even days later. Warning signs include blurred vision, visual distortion, or the appearance of a central blind spot known as a scotoma, which can make everyday activities such as reading or focusing on an object difficult. In the most serious cases, exposure can cause a macular hole, an injury that may require surgical intervention. The IAC stresses that looking at the Sun for just a few seconds, if done repeatedly and without proper protection, can cause cumulative damage.

The safest way to watch: indirect projection

The primary recommendation from the Canary Islands Astrophysics Institute is to observe the eclipse through indirect projection. This method involves projecting the Sun’s image onto a surface, such as a piece of card, a wall or a screen, without looking directly at the star itself. Projection allows viewers to follow the progress of the eclipse without exposing their eyes to direct solar radiation. It is a system particularly recommended for educational activities, family groups, or public spaces where many people want to observe the phenomenon at the same time.

Certified glasses only: what to look for

For those who wish to observe the Sun directly, the IAC reminds the public that only certified glasses meeting the EN ISO 12312-2:2015 standard, specifically designed for direct solar observation, should be used. This certification is not the same as that of ordinary sunglasses. Standard sunglasses, even dark ones, do not block enough solar radiation to protect the retina.

During total eclipses, such as those in 2026 and 2027, it is only safe to remove the glasses during the minutes of absolute totality, that is, when the Moon completely covers the Sun and the surroundings go dark. Outside that brief window, protection must be maintained at all times. This includes the partial phases before and after, when part of the Sun remains visible and continues to emit enough radiation to damage the eyes. In locations where the eclipse is not total, you should never look at the Sun without approved protection or without using indirect projection methods.

Homemade methods: a firm no

The IAC is categorical about homemade methods: sunglasses, smoked glass, X-ray film, CDs, photographic film, and improvised filters for binoculars or telescopes are all unsuitable. The only relatively acceptable homemade method, albeit with optical limitations, is the use of a high-grade welder’s glass or filter, between shades 12 and 14. Even so, the preferred recommendation remains to use certified glasses or to rely on solar image projection.

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