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Unlocking the Mysteries of the Sun: An Interview with Prof. Shadia Habbal
Professor Shadia Habbal, an astrophysicist at the University of Hawaii, Institute for Astronomy, devoted her career since 1995 to exploring the Sun's corona through total solar eclipse observations. Her pioneering work illuminates the complex interplay between magnetic fields, solar wind, and coronal structures. In this interview, she discusses the human side of scientific expeditions, the evolution of solar research, and the enduring mysteries of our host star.
Prof. Habbal collaborates closely with Miloslav Druckmüller from the Faculty of Mechanical Engineering at Brno University of Technology (BUT), employing innovative imaging techniques during solar eclipses to study the Sun's magnetic structures and plasmas in unprecedented detail. Their research has unveiled critical connections between prominences—cool, dense structures on the Sun's surface—and coronal mass ejections (CMEs), advancing our understanding of the Sun’s dynamic atmosphere. In recognition of this long-term scientific partnership, Prof. Habbal was awarded an Honorary Doctorate by BUT on November 29, 2024.
Prof. Habbal, when I say "the Sun," what are the first words that come to mind?
Before I began my research in solar physics, my perception of the Sun was completely different. Now, for me, the Sun is the source of incredible intellectual joy. When I look at it, I no longer see just a bright object in the sky; I see a complex system of fascinating physical processes. What we learn from the sun applied sheds light onto what we can learn from other stars, so people get inspired, and get their ideas from all the knowledge we have gained from studying the sun and its outer atmosphere, the corona.
The Sun is our closest star, and understanding its behavior isn't just an academic pursuit. It's vital for space weather prediction, which has a direct impact on our technology-dependent society.
What initially drew you to solar physics?
It was pure chance. I did my PhD in a process that happens with magnetic fields in a plasma, I studied magnetic reconnection. The applications were mostly for the Earth's magnetic environment as it interacts with the solar wind and the magnetic field of the the sun. I had read quite a few papers on the solar wind, but my focus was the physics of the process, not the sun itself.
Then I applied for a postdoc position at the National Center for Atmospheric Research, and I got accepted. One of the researchers met me at the conference and said: „I read your application and I would like you to work with me“. I knew his name from the literature, but I had never met him, so I was very happy. And that's how I started my research in solar physics: it started as a pure chance, just meeting this person at a conference.
You're the head of the Solar Wind Sherpas. Having worked across different institutions and cultures, how do these experiences shape your scientific collaborations and perspective?
It has been the most rewarding career! I always wanted to research since I was 9 or 10 and I read about Marie Curie, she was my idol. That was my dream, but I never thought my dream would take me so far across the world, working with different people, especially with Miloš Druckmüller and his group. They're like a second family now. It was intellectual „love at first sight“.
Your research often involves expeditions to remote locations. What is it like working in such challenging environments?
These expeditions are as much about human resilience as they are about science. Traveling to remote parts of the world to catch the brief moments of a total solar eclipse requires intense preparation and adaptability. It is incredibly rewarding—both scientifically and personally. You travel to these different parts of the world and you see that the fabric of humanity is the same. There are no barriers between human beings, all these geographical or political boundaries are so artificial.
The success of these missions depends entirely on the dedication and creativity of the team. Everyone brings unique expertise, and there is a shared understanding that mistakes cannot be afforded during these fleeting opportunities. I’ve been fortunate to work with incredibly talented individuals who are motivated not by financial gain but by the excitement of discovery and the experience of being part of something greater. You won't find it in a normal office setting.
When you started your career, I can imagine it wasn´t easy for a woman in the field of astrophysics. However, your work has also challenged some long-standing assumptions in solar physics, right?
My career has not been easy. I felt like walking on a tight rope, for a long time. Because the system, especially in the United States, is very competitive, you have to prove that you can do something original and it was also a matter of people accepting your ideas and you telling them how you saw things. One of the advantages is I came into the field as an outsider, so I had a different perspective.
One of the key findings I was involved in, is that solar wind doesn’t originate solely from the Sun’s polar regions, as was long believed. Early models assumed this based on limited observations, but our eclipse data showed that open magnetic field lines, which guide the solar wind, are present across the Sun's surface. This overturned established theories and opened new avenues for understanding how solar wind impacts space weather and interplanetary conditions.
What are the unique advantages of studying the solar corona during total solar eclipses compared to using space-based instruments?
The only time you can see the corona with your eyes is during a total solar eclipse. From space, you can go to the UV, EUV and X-rays part of the spectrum and you can see all the structures. But you don't see very far away from the Sun. With a total solar eclipse, you don't see the sun because it's obstructed by the moon, but you see the corona out to several radii. And that's what's so fascinating – because you're capturing the gas and the magnetic fields as they're leaving the sun and escaping into interplanetary space, and you can see it visually. That's very special. At the moment, there are no instruments in space that can reproduce what we're getting during eclipses.
There is also another „but“: images you capture with the camera are not as good as what you see with your naked eye. You have to take different exposure times and combine them afterward. Before meeting Miloš, we did it in a rather crude way. When Miloš processed our data for the first time, I couldn´t stop looking at the picture, it was so beautiful. What Miloš is doing is extremely important because it gives us the chance to see what´s happening in the corona. It is – literally – the beauty of science.
Your work also suggests a strong link between solar prominences and the initiation of coronal mass ejections, so-called CMEs. What are the most surprising findings about their interactions so far?
Our understanding of prominences has evolved significantly. We now know that they're not just passive structures – they play an active role in these massive eruptions or CMEs. What surprised us the most was the intricate relationship between the magnetic field and these cooler structures.
The prominence is much more cooler, about 10 000 K and the rest is at 2 million K. It sits at the heart of a magnetic "cage," and when certain conditions are met—like magnetic reconnection or destabilization—the prominence becomes a trigger. It's almost like a domino effect. The energy stored in the magnetic field is released, launching the prominence material and the overlying corona into space.
What's fascinating is how finely balanced these systems are. It's like a dance between stability and instability. Sometimes, the prominence just oscillates or changes shape but remains intact. Other times, it completely erupts, leading to a CME. This behavior is still not fully understood, and it's one of the challenges we're actively working on.
The sun's magnetic field is a complex and dynamic environment. What challenges do these complexities bring to predicting solar activity?
Enormous challenges! You don´t know what's pushing them to behave the way they do. It's a very complex and difficult system, but at least we're making some progress in recognizing the direct link between the prominences and the overlying coronal structures.
Could you name some of the most pressing questions about the Sun’s corona that you hope to answer in the coming years?
The reason I got interested in doing eclipse observations is that when I was doing models trying to understand the physical conditions that make a stream of wind go fast and as well as its average speed for the most time. The solar wind speed at Earth can vary from 300 to 800 kilometers per second. In the models, it was very important to know the temperature as close to the sun as possible. This is why I started to do eclipse observations: because I knew with the total solar eclipse you can get very close to the surface and different spectra are coming from various charge states of iron. And they would give us a map of the temperature in the corona.
But then what happened to my surprise I looked at all the observations from charged particles, in particular Fe, and found that the Fe ions originating from the sun and escaping with the solar wind tend to preserve their identity. As if it was saying „this is where we came from in the corona“. Why this is the case, I don´t know. What is causing the sun to behave like a pressure cooker where the temperature doesn't go up, but something is holding it down? This is the big question for me: What is causing this temperature to be so constant? So that's a new puzzle to be solved.
Source: Faculty of Mechanical Engineering BUT
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