On Wednesday, 12 August 2026, a total solar eclipse took place. The expedition of mathematicians from the Faculty of Mechanical Engineering at Brno University of Technology (FME BUT) has now completed its most demanding stage. How did the teams in Spain fare? And how did the weather treat the researchers in Iceland? In the final instalment of her expedition diary, mathematician and FME Vice-Dean Jana Hoderová describes what happened on the day the Sun disappeared behind the Moon.

Wednesday, 12 August: Eclipse Day

After a year of preparations, the day we came here for has finally arrived. Over the past few days, we have done everything in our power. The equipment is ready, the cameras are focused, we have collected some of the calibration data, and we have rehearsed the “live start” several times at the exact time of the eclipse. Now only one thing remains beyond our control: the weather.

Jindra sets off in search of a better forecast

Based on the morning forecast, Jindřich Nový makes the final decision to leave Flateyri and move approximately 100 kilometres south. He sets off early to avoid the announced traffic restrictions. From 8 a.m., some roads through the fjords are due to become one-way, while only a limited number of cars will be allowed onto others. Selected observing sites will be accessible only by shuttle bus.

Before long, the first photographs arrive from him. His mount is standing on a cliff above the sea. It is a spectacular location, and it would be difficult to imagine a more impressive backdrop for a total solar eclipse. Now he just needs the magnificent setting to be matched by a magnificent sky.

We now have three observing sites in Iceland: Flateyri, Stykkishólmur and Jindra’s mobile site south of us. Only two of the Icelandic locations, however, have the full set of equipment for the unique experiment led by Professor Miloslav Druckmüller and Shadia Habbal, which focuses on observing specific iron ions in the solar corona.

We have another three fully equipped observing sites in Spain. At this point, it is no longer about which of us gets lucky. Success at any one observing location means at least partial success for the entire expedition. That is precisely why we divided both the team and the equipment among several sites.

Sky reports from the individual locations

Throughout the morning, photographs of the sky keep arriving on WhatsApp from the different observing sites. Forecast models are one thing, but photographs of the actual sky tell a much clearer story.

In Iceland, we are still hopeful in the morning. In Stykkishólmur, however, resignation sets in fairly quickly. First there is drizzle, and then it starts raining directly onto the equipment. The three mounts under rain covers look rather forlorn.

Jindra sends increasingly desperate photographs of the sky. Eventually, we can see water droplets on the solar filters covering his lenses. Unfortunately, even a beautiful location on a cliff is not enough.

Flateyri holds out the longest. Even during the morning, we continue fine-tuning the equipment and doing everything exactly as if the sky were going to be clear. An hour before totality, we are still clinging to hope. There is a gap in the clouds. All it needs to do is move in the right direction at exactly the right time.

Meanwhile, conditions in Spain look stable. The situation there is completely different: Spain had the most promising long-term cloud forecast.

Flateyri waits for the eclipse

But an eclipse is not only about a scientific experiment. In Flateyri, its human dimension is also clearly visible.

A large number of people have arrived in the village, and we estimate that its population has at least doubled. Portable toilets have been installed in places where larger crowds are expected. People are having picnics, lying on blankets on the grass or sitting on rocks around the fjord. They talk, but above all, they keep watching the sky.

In fact, something very similar is happening back in Czechia. Friends and family members keep sending us photographs of a beautiful partial eclipse under clear skies. People there, too, are gathering together, putting on eclipse glasses and watching the Sun.

And Helen and Siggi? They have set themselves up on the roof of their house. Our three mounts are standing below in their garden, next to the wall, while they enjoy the eclipse with us from above. After a week of sharing their home, our problems and our moments of joy, it feels entirely natural that they should be here with us now as well.

We are ready. Really ready

Pavel Mikuláček and I make the most of eclipse day. We run through the entire planned exposure sequence once again. We count it down, remove the solar filters and check that the required images are actually being captured.

And we have also allowed ourselves one small pleasure that does not compromise the experiments in any way. Our mounts are standing in Helen and Siggi’s garden, but we do not want to experience totality surrounded only by the house, computers, equipment and a hedge. At least for a moment, we want to look out across the open landscape with our own eyes during the eclipse.

So we practise starting the sequence, removing the filters, checking the equipment and then running about twenty metres from the garden to the shore of the fjord. That is where we want to experience the visual beauty of the eclipse. Then we will quickly run back again so that we can cover the lenses before direct sunlight returns.

We rehearse the whole sequence twice. We are ready.

The sky, unfortunately, is not.

The eclipse approaches and the tension rises

Totality is getting closer. We do everything we have rehearsed so carefully. We start the programmed sequences and remove the filters.

But we are not in any hurry.

By now, we already know that our data will be unusable.

Even so, we run those twenty metres to the shore of the fjord. If the clouds will not allow us to see the solar corona, we at least want to experience what they cannot take away from us.

True darkness arrives. It lasts for 1 minute and 44 seconds.

We stand by the fjord and look towards its mouth. Above us, the sky is overcast and we are inside the Moon’s shadow. But far ahead, on the horizon, we can see ordinary daylight. The path of totality does not extend that far.

The contrast is fascinating: darkness all around us, daylight on the distant horizon.

We cannot see the solar corona. Yet we know exactly what is happening above the clouds.

And then it is over.

This time, there is no euphoria

After a successful observation of a total solar eclipse, there is usually an enormous sense of euphoria. Spontaneous cheering, joy, emotion.

Not this time.

Instead, sadness and a sense of helplessness set in. At a moment like this, you suddenly realise just how much work lies behind those less than two minutes. A year of preparations, equipment upgrades, testing, packing, the journey to Iceland, a lost suitcase, wind, rain, a troublesome screw, the battle with focusing, calibration data, repeated rehearsals.

And then all it takes is a layer of cloud.

Siggi, Helen and I take a rather sad photograph together.

But moments later, we take another picture. This one is cheerful.

We are already looking ahead to the future, to the next eclipse.

There was nothing more we could have done in Iceland, and now we wait anxiously for news from the others.

What about the others?

We are no longer expecting much good news from Iceland. Stykkishólmur was washed out by rain. Jindra’s attempt to escape in search of better weather did not work either. And we in Flateyri have just experienced totality beneath the clouds.

But we still have three observing sites in Spain.

And good news is coming from there.

Spain succeeded. We have the data

Our feelings are mixed. Of course we envy the teams in Spain, but we are also genuinely happy for them. We were in Iceland, we were prepared, and we desperately wanted to see the corona and bring back our own data. Thanks to the time difference between totality in Iceland and Spain, it would have been possible to analyse the dynamics of the solar corona over time.

One team’s success is everyone’s success

This is exactly the moment that shows why we planned the expedition from the outset as a network of several observing sites. If all of us had been standing together at a single location in Iceland, a year of work would have ended beneath the clouds.

We divided the people, the instruments and the risk. The weather failed us in Iceland, but it worked in Spain. Our multi-site strategy therefore worked almost perfectly.

Unfortunately, those of us in Iceland became a very clear demonstration of exactly why that strategy was necessary.

The overall outcome of the expedition is positive.

We have the data.

Miloslav Druckmüller now has a huge amount of work ahead of him processing them. And the rest of us, along with all eclipse enthusiasts, will be eagerly waiting to see what can be found in the data and what Miloš will eventually show us in his public lectures.

Even an unsuccessful observing site is not wasted

There is one more important point. Before an expedition, we test everything under comfortable laboratory conditions. In warm, dry offices, the equipment works exactly as we need it to.

Real-world conditions, however, bring surprises that cannot be simulated back home. Wind, rain, humidity, different possibilities for setting up the mount, mechanical play, and focusing that works perfectly on one camera but not on another.

That is when you need to stay calm, identify the cause, work through the problem systematically and, every now and then, add a healthy dose of improvisation.

That is why even an unsuccessful observing site is useful. We know a little more than we did before, and we will be a little better prepared for the next expedition.

And that is really what it is all about.

In the end, the people matter most

We have an amazing team. Some members have already experienced many total solar eclipses, including Miloš Druckmüller and Pavel Štarha. Others have much less experience. Some are still waiting for their first successful observation of totality.

A large part of our team consists of students from the Faculty of Mechanical Engineering at Brno University of Technology. And expeditions like this teach them something that is difficult to learn in a lecture hall alone: how to cope when things do not go according to plan. How to think, cooperate, look for solutions and not give up on a problem simply because the manual never anticipated a situation like this.

We will not be bringing images of the solar corona back from Iceland this year. But we will bring back experience that we can use next time.

Most importantly, we now know that the strategy of dividing our equipment and team among several locations works. Success – even if achieved at just one observing site – is a success for the entire expedition.

The result is not the work of one person or one camera, but of the whole team.

I would therefore like to thank the entire team for their excellent work, commitment and ability to cope with situations we could never have planned for in advance. I wish everyone a safe journey home.

We would also like to thank all our supporters, families and friends who followed our journey, sent us messages and kept their fingers crossed for us.

Did you miss the previous instalments of mathematician Jana Hoderová’s diary from this year’s total solar eclipse expedition? Read Part One and Part Two.