The solar corona is the Sun's outer atmosphere: an envelope of plasma at over one million degrees that surrounds our star and extends millions of kilometres into space. Under normal conditions it is invisible. You will see it on 12 August 2026 — but only if you are in the right place.
What is the solar corona
The Sun has layers. The one we normally see — that bright sphere in the sky — is the photosphere, the visible surface. Above it lies the chromosphere, and beyond that, stretching millions of kilometres into space, is the corona.
The corona is an extremely tenuous and hot plasma. Its temperature exceeds one million degrees Celsius — paradoxically far hotter than the surface of the Sun itself, which is "only" around 5,500°C. Why the corona is so much hotter than the surface is one of the most important open questions in astrophysics today.
"The corona emits very faint light. The reason is that it is approximately 10 million times less dense than the surface of the Sun."
— NASA Space Place
That extremely low density means that, even though the corona is enormously hot, it emits very little light. And that faint light is completely overwhelmed by the brutal brightness of the photosphere. The result: the corona is invisible to the naked eye under normal conditions, even though it is always there, vast, surrounding the Sun.
Why it can only be seen during a total eclipse
Scientific instruments called coronagraphs attempt to block sunlight artificially in order to study the corona from observatories and satellites. But even with these, the innermost region of the corona — the most important for understanding the solar wind — is difficult to reveal.
A total eclipse does what no human instrument can perfectly replicate: the Moon covers the solar disc with millimetric precision, blocking exactly the photosphere without obscuring the corona. During those seconds, the Sun's outer atmosphere is laid bare and visible to the naked eye from Earth.
Only during totality. Outside the 112 km path, the eclipse is partial — the Sun is never completely covered and the corona remains invisible. There is no middle ground: either you see the full corona, or you do not. An eclipse with 99% coverage does not reveal the corona.
This is why total solar eclipses are particularly important to scientists: they allow observation of the corona, which is too faint to be seen except when the Sun's bright disc is blocked. And for the rest of humanity, it is simply the most breathtaking spectacle that exists in the sky.
What you will see exactly during totality
The sequence lasts between a few seconds and just over a minute and a half depending on your location within the path. This is what will happen:
- Diamond ring — in the last seconds before totality, the Sun emits one final bright flash combined with the emerging corona. As the last rays of sunlight pass through the valleys on the Moon's limb, the corona begins to appear, creating a ring studded with brilliant diamonds.
- Chromosphere — a crimson halo surrounding the Moon for a few seconds before totality is complete.
- The corona in full glory — the solar corona is revealed flowing into space above the Sun's surface. You will see filaments, prominences and structures shaped by the Sun's magnetic fields. Nobody who has seen it ever forgets it.
- The lit horizon — while the sky above you is dark, the horizon in every direction shows the colours of sunrise. The Moon's shadow moves at 3,000 km/h and you will see it arrive.
- Stars and planets visible in daylight — Venus and Jupiter will be visible in broad daylight during totality.
The 112 km path: why your location is everything
The Moon's shadow on Earth has a diameter of around 112 kilometres. That shadow sweeps across the Earth's surface at great speed on 12 August 2026, and in Catalonia it crosses a path that enters through the south of Tarragona and exits towards the south of Lleida.
If you are within that path: total eclipse, corona visible.
If you are outside it, even just 1 km further north: partial eclipse, corona invisible.
Much of the province lies within the path. This includes the coast (Cambrils, Salou, Tarragona city), the interior (Reus, Valls) and the Terres de l'Ebre (Tortosa, Amposta, the Delta). Some municipalities in the north of the province fall outside.
The path enters through the south of Lleida. Les Garrigues and part of the Segrià are within it. The rest of the province — including Lleida city — falls outside or on the boundary with only a few seconds of totality.
Barcelona city and the entire province will see an impressive partial eclipse — the Sun covered by 90% or more — but with no solar corona and no total darkness. To see the corona it will be necessary to travel south.
The province of Girona falls entirely outside the path of totality. The percentage of solar coverage will be high, but the experience of totality — and the corona — will not be visible from here.
In total, 221 municipalities in Catalonia have confirmed total eclipse, according to official data from the Instituto Geográfico Nacional (IGN) and the National Astronomical Observatory. The duration of totality varies: the municipalities of the Ebro Delta are the most privileged, with nearly 100 seconds of visible corona. As you approach the northern limit of the path, the seconds decrease.
Will your town see the solar corona?
Before planning where you will be on 12 August, check whether your town is within the path — and if so, exactly how many seconds of totality you will have. We have built the search tool using official IGN data for the 221 municipalities with totality in Catalonia.
👉 Use the home page search tool to check your municipality in real time → eclipsi26.com → search section
The 221 municipalities
with total eclipse in Catalonia
We have compiled the official IGN and National Astronomical Observatory data into a downloadable PDF: the 221 municipalities with total eclipse, their exact start, peak and end times of totality, and duration in seconds. Save it on your phone or print it before 12 August.
Instant download
What you need to see it properly
The solar corona is visible to the naked eye during totality — no glasses, no telescope, nothing required. But for the rest of the eclipse, and to photograph it, you do need basic equipment:
- Certified ISO 12312-2 glasses — essential during all partial phases. They come off during totality. Outside totality, never look at the Sun without them.
- A tripod if you want to photograph it — the corona is faint and you will need slow shutter speeds to capture it well on your phone.
- Know your exact times — knowing when totality starts and ends in your specific municipality is critical. Do not improvise.
- Arrive early — the municipalities in the path will receive visitors from all over Spain and Europe. Arrive at least two hours beforehand.
The solar corona cannot be seen from a living room in Barcelona, from the beach at Sitges, or from the Tibidabo. Only from within the path. Plan your journey weeks in advance — that day the roads of southern Catalonia will be a spectacle of their own.
Scientific content based on: NASA Science, NASA Space Place, Instituto Geográfico Nacional (IGN), National Astronomical Observatory.