April 13, 2024

Why a solar physicist has been chasing solar eclipses for more than three decades

On Monday, April 8, millions of people will be able to see the Great North American Eclipse. Most people on the continent will see a partial solar eclipse, with the Sun gradually dimming as the Moon passes in front of it.

But if you’re in exactly the right place — along the narrow path of totality that runs from Mexico to Indianapolis and Montreal — the Moon will line up directly in front of the Sun and block it completely.

“When that happens, it feels like magic. It looks otherworldly,” says Shadia Habbal, a professor of solar physics at the University of Hawaii. “It hits you in every part of your body. You simply feel something is around you. Something is taking you to a place you have never been before.”

When the moon completely blocks the sun, it’s the only time you can see the sun’s atmosphere, the corona, which is made up of particles constantly moving away from the sun. “Sometimes they run away happily,” says Habbal. “But sometimes you have what we call a solar storm or solar flare.”

The sun’s corona is visible as the moon obscures the sun during the 2017 total solar eclipse.
Carlos Avila Gonzalez/The San Francisco Chronicle via Getty Images

Radiation from solar storms often ends up reaching Earth, which can lead to beautiful phenomena like the aurora borealis. But it can also cause huge problems, such as disruptions to the energy grid, major blackouts or even the downing of satellites.

Despite the damage solar storms can do to our technology on Earth, scientists are still struggling to predict them. And that’s because they don’t understand much about how corona works.

Even though it extends millions of miles from the Sun’s surface into cold, icy space, the corona is still a million degrees hotter than the Sun’s surface. And scientists aren’t sure why. This is why Habbal became an eclipse chaser.

I recently spoke with Habbal for an episode of Inexplicable, the Vox podcast that explores scientific mysteries, unanswered questions, and everything we learn by delving into the unknown. This conversation has been lightly edited and adapted for the website.


Noam Hassenfeld

You’ve been chasing solar eclipses for almost 30 years. You even founded a group, Solar Wind Sherpas, whose mission is to chase eclipses. How did you become interested in studying these phenomena?

Shadia Habbal

I was making models of the crown, trying to figure out what processes heat the crown. And I realized that temperature was critical information that I needed to have. But the data available at the time didn’t give me the answer I was looking for. So, I knew that eclipses were the main observations to arrive at this answer.

Noam Hassenfeld

So the first eclipse you saw was when you were already researching the corona?

Shadia Habbal

Yes, the first solar eclipse I saw was in 1995, in India, and it was a very, very short eclipse. It was 42 seconds long, but it was probably the most spectacular I’ve seen. The eclipse happened around 8am. And when that happened, I saw the corona, these rays upon rays expanding from the Sun, stretching out to infinity, visually. But we only had 42 seconds, so I couldn’t spend too much time looking around or anything. We had to pay close attention to how the cameras we had worked. I thought, “Okay, one measurement and that’s it.” But we realized that one was not enough. We had to keep trying.

Noam Hassenfeld

Where have you and your team been since then?

Shadia Habbal

We were in Mongolia. We’ve been to Antarctica. We were in Libya. We were in Tatakoto, French Polynesia. To Svalbard, you know, northern Norway, beyond the Arctic Circle. We were in Syria, Chile, Argentina, Zambia and South Africa. And this will be my 20th.

Noam Hassenfeld

Why do you need an eclipse to study the corona? Can’t you do it artificially, put something up to block most of the sun?

Shadia Habbal

Well, because it doesn’t work as well as a natural eclipse.

Noam Hassenfeld

Why don’t you do such a good job?

Shadia Habbal

It is a very small blocker, while the moon is huge. Therefore, it dims the light to the point where the sky appears nighttime.

Noam Hassenfeld

Oh okay. Let’s say I go out and want to study corona. If I held a coin in front of the sun and blocked the sun, I still wouldn’t see the tail because the coin is too close to my eye. Everything would be filled with sunlight.

Shadia Habbal

Yes. With an eclipse, you get very complex structures very, very close to the sun, and everything is flowing out as you look further away. So you see this seamless transition from the surface to the outside that you don’t get with any other instrument at the moment.

Noam Hassenfeld

What instruments do you use when studying the eclipse?

Shadia Habbal

Our optical systems are like very small telescopes. But the key element is something we call a spectrometer, which is like a prism when you let light pass through a prism and it splits the colors, and so we capture these different colors. And each color corresponds to a different temperature in the crown.

Noam Hassenfeld

Is it fair to say that you are creating a temperature map of the corona?

Shadia Habbal

From corona, yes, exactly.

Noam Hassenfeld

And will this map help make these models of how the crown works more accurate?

Shadia Habbal

Yes, exactly.

Noam Hassenfeld

Are we close to being able to use some of these models to say, “Okay, do we have to prepare the power grid, do we have to prepare the satellites for a solar storm?”

Shadia Habbal

Not yet. We have some clues. We know what is causing them, but we cannot predict when they will happen. And that’s one of the things we’re trying to gather more information from our eclipse observations.

Noam Hassenfeld

Are we closer than we were 30 years ago?

Shadia Habbal

Yes, but we don’t have a complete answer yet… we don’t have a reliable answer.

Noam Hassenfeld

I like that you can laugh about it. What would you say is the biggest obstacle in observing eclipses or chasing eclipses?

Shadia Habbal

The weather.

Noam Hassenfeld

Right now I am laughing.

Shadia Habbal

And truth! We lose 40% of our observations to clouds.

Noam Hassenfeld

Wow, 40 percent?

Shadia Habbal

Hmm.

Noam Hassenfeld

So how many eclipses?

Shadia Habbal

20. For example, this would be my 20th. We lost 40 percent. We lost eight.

Noam Hassenfeld

I imagine this must be very disappointing.

Shadia Habbal

Well, it’s heartbreaking, yes. Because, then, a lot of times what happens during, just a little bit before totality, the temperature drops and you have atmospheric conditions that happen suddenly. Once in South Africa, the sky was perfectly clear and a cloud formed right in front of the sun, just before totality. Here was a cloud, just decided be right in front of the sun and then dispersed by the time the eclipse ended.

A bird flies in a dark, cloudy sky below the sun, which looks like a partial crescent due to obstruction from the moon.

The moon partially eclipses the sun as clouds largely obscure the sky in Odesa, Ukraine, October 25, 2022.
Yulii Zozulia/Ukrinform/Publicação Futura via Getty Images

Noam Hassenfeld

So you’re set up, you have your equipment, a cloud appears and that’s it? Can’t you do anything?

Shadia Habbal

Yes, you lost everything. You have no data. And another time we were in Kenya, we had a sandstorm just 15 minutes before the eclipse. We were near a lake and basically the wind pattern changed. And then suddenly we were looking at the sun and a colleague of mine turned around and said, “Oh! Y… H—” [Habbal begins to spell the word — you know which one — and then stops herself] I said, What’s the problem?” We looked back and a huge cloud was coming towards us.

Noam Hassenfeld

What did you do?

Shadia Habbal

We cover the equipment. We had to. It was very, very fast. And we were completely cloudy.

Noam Hassenfeld

It seems like there must be a better way to do this.

Shadia Habbal

Well, there are ways. We were recently in Antarctica and unfortunately it was cloudy. It was really painful because the sky was crystal clear the day before. And crystal clear two hours after totality. One of my colleagues came up with the idea and said, “Why don’t we fly a kite?”

Noam Hassenfeld

Flying kites?

Shadia Habbal

Well, not just any kind of kite. It is quite large, with a wingspan of around 6 and a half meters. We attach a spectrometer to it. The idea is that if it’s cloudy with a kite you can go up 4 to 5,000 meters and get above the clouds, and we tried that last year in Australia.

Noam Hassenfeld

What was it like testing something like that? Were you nervous?

Shadia Habbal

Yes, we were very nervous, but it was a very emotional experience. It was like watching Sputnik. And the other option we’re trying this year is [working with] NASA’s research aircraft called WB-57. Now this plane flies up to 60,000 feet where there are no clouds.

Noam Hassenfeld

And is this plane flying in the path of totality?

Shadia Habbal

Exactly. The engineers and pilots of this NASA project can follow the path of totality.

Noam Hassenfeld

How close are we to being able to predict corona? Are all these measurements helping with these predictions?

Shadia Habbal

Yes, but like any scientific research, you discover something and then discover that there is much more to discover. This is the beauty of scientific research: you are never done.

Noam Hassenfeld

So, will you continue chasing eclipses for the rest of your career?

Shadia Habbal

I’ll keep chasing eclipses until I can’t chase them anymore, and then someone else will have to do it.

Leave a Reply

Your email address will not be published. Required fields are marked *