Pastoor Schmeitsprize for Yamila Miguel

Exoplanet research appeals to the imagination of young and old alike. The ultimate goal of many astronomers in this field is to find a habitable planet orbiting another star, one that resembles Earth. In 2024, for the first time, humanity studied the atmosphere of a rocky planet outside our solar system.

Important theoretical work was done by theorist Yamila Miguel. With her team, she spent years describing with computer models what we might see in our early search for rocky planets with atmospheres. For this, she was awarded the Pastoor Schmeitsprijs in May 2025. What exactly was that theoretical work? And how did she come to do it?

“I tried to imagine what an atmosphere might be like on a planet with oceans of molten rock.”

“There are still so many things we don’t know about other planets. About exoplanets, but also about planets in our own solar system. We have been studying our solar system for a long time, and still we don’t know how planets form, how planets evolve, and how they work. We know tiny pieces of the process. It’s like a puzzle, and we’re just missing all the other pieces.”

“I want to understand how planets work, from the inside all the way to the outer layer, the atmosphere and the interaction between the inner and outer layers. I do this by developing computer models, based on what we already know about planetary physics.
In our solar system, I study Jupiter, Saturn, Uranus and Neptune, so mostly the giants. But I’ve also been researching exoplanets for many years, particularly small rocky planets and what they might look like. Stony planets similar in size to Earth, Venus, Mars and Mercury, very different from the large gas planets in our solar system.”

“As for the solar system, of course, we have been observing planets for centuries, so there is a lot of information. And there are many data we didn’t have before. Take Jupiter, for example. With the Juno mission in a special orbit around Jupiter, we saw that the orbit does not correspond exactly to what you would expect according to your theoretical model, assuming a perfectly symmetrical planet shape.

Deviations from the perfect trajectory to the real trajectory are telling us that there are inhomogeneities in the interior of the planet. And that is what I used to model the interior of the planet. There is more material accumulated in certain places compared to others.
We learned that the material accumulated in the core of the planet is also being diluted a little bit into the gaseous envelope. We didn’t know that in the past.
We had previously assumed that the core, made of rock and ices, was completely separated as a distinct layer, from the gaseous envelope. Now we know that’s not true. It’s slowly diluted.

And that changes everything in the interior: how energy is transported, how material is transported, how the atmosphere and interior of the planet interact, how the planet formed, how it evolved… It has a lot of consequences that we now have to figure out.”

“The data from Juno was so good that we had to update our methods. By aligning our methods with those excellent measurements and updating them, we were able to improve them significantly.”

“The solar system differs from exoplanets in how we can study them. In the solar system we can go there, we can make measurements, but you do this for one object. With exoplanets, well… we cannot go there. But we’ve observed about 6000 of them from far away, although not all rocky.
So when you have a population, it’s easier to understand the gaps that maybe you missed when you studied only the few objects nearby. That’s why I like to combine things.”

“I’m a theorist, so I work towards trying to understand and explain the observations using computers and physical models. For this, I feed myself with data. I believe that in general, the physics of how planets work should be more or less the same. With some different effects of course, depending on the cases.”

“For exoplanets, I use James Webb Space Telescope data. What I like to do is build models on the computer, to try to understand the data that we see. I try to link the methods, the models, and the information that we obtain from one research field to the other. That’s what I got a grant for from the European Research Council: to learn things from the solar system and apply them to exoplanets and vice versa.”

“The rocky exoplanets we are observing now are completely different from the solar system ones. They are much hotter, and many of them are much closer to their stars than Mercury is to the Sun.
That doesn’t tell us whether our solar system is special or not. We can’t tell because we can only see the exoplanets we can detect so far, with the technology we have now. But the data from the rocky exoplanets we do have is very different from that of the solar system ones.”

“A lot of people who work with rocky planets are interested in habitable planets like Earth because of course that’s the ultimate goal. We want to know if there are other planets like our own.
But my point about the hotter rocky planets was: ‘Okay. We have hundreds of them. We don’t know much about them. But we can observe them with the technology that we have. And we cannot observe the others. So why not observe these ones, and learn about their atmospheres, their interiors, their evolution and see if this can teach us something about the other ones like Earth, that we’re more interested in?’”

“When I started to work with rocky planets more than ten years ago, there was still no data at all. Nothing, except we knew of their existence. So I started with an idea.
The idea was that these planets are so close to their stars that they have a magma ocean, with temperatures above 2000 degrees. Any rock on the surface must then be molten, and these rocks are vaporized, and this is what makes the atmosphere.
Imagine you have this magma, made of certain materials… What would the atmosphere then be made of? And what could be things we could possibly observe in these atmospheres, if anything?
And what would happen if you had other gases in that atmosphere — how would they interact with your magma?
So this was all purely theoretical research. I based the composition of this magma on our knowledge of planets in the solar system. Earth was also once such a hot planet.”

“Because of these models, we had an idea what to search for and what we might find. So we could write proposals to request observing time on the James Webb Space Telescope.
With the models, we could show what we might observe, so they gave us the time to observe these planets.”

“So last year, with James Webb, we detected an atmosphere on a rocky exoplanet for the first time: that of 55 Cnc e. The Schmeits Prize is for all the theoretical work my team and I did to understand atmospheres of such planets.”

“It’s very exciting. It’s very difficult to be granted observing time on such an expensive telescope. You need to convince a panel that you can observe something. That’s why the models are important. Models convincingly demonstrate that the data will tell you something.
To get observing time from James Webb was a chance of approximately 1 in 7. And we now have data from other planets too, which we are analysing…”

“We are now re-examining some of the phenomena we published about in the past. For example, the data hint that there may be CO₂ in the atmosphere, but we are not completely sure yet. So it’s very interesting to have data for the first time, on something that I’ve been working on for so long. It sparks more curiosity, and I’m involved in more proposals for exoplanet observations, so… there is more data to come.”

“Now I’m working on the Ariel mission that will fly in 2030. I’ve been working on that mission since 2016. Ariel is an exoplanet mission, exclusively observing atmospheres of exoplanets. 100% exoplanets, as opposed to the James Webb Space Telescope. We get a little proprietary period for observations too. In the mission science team I’m the co-principal investigator for the Netherlands.”

‘I’m doing it for future generations. Others started working on the Juno Mission too when I was just starting in astronomy, so I could eventually work with the data.

“Curiosity, but all scientists are curious, you need it to be a scientist. And it takes patience too. Some space missions take a lot of time from the idea to the mission providing data. But you know that you will be doing your work for the future generations. Although with Ariel I will hopefully see the results, we’re now thinking of a mission to Uranus, for example. Going there takes so long, I’m not even sure I’ll still be working or even retired when the data arrives. So you keep in mind that you are doing it for the future generations, and that people in the past did this for you.
Like the Juno mission. That started being planned in 2000. I was just starting out in astronomy back then. So others were working on this mission so I could eventually work with the data. Astronomy is like that. That’s the way this science works. Timescales are something you learn to deal with.”

“And also to work as a community. These missions are so expensive that you need to team up with others in your country, in your continent, and even across continents, ESA, NASA, JAXA and other space agencies. That’s one of the admirable things about how astronomers collaborate.”

“I like that way of doing science. Instead of competing with others to work together toward the same goal.”

Yamila Miguel teaches as an associate professor at SRON and Leiden University. She developed the course module on exoplanets at the faculty in Leiden, which also earned her the title of “Teacher of the Year” in 2023.

She has received prestigious grants, for example, from the Netherlands Organisation for Scientific Research (NWO) for her research with Juno on Jupiter, and in 2023, a Consolidator Grant from the European Research Council for her exoplanet research. She was awarded the Pastoor Schmeits Prize in May 2025.

She is also the principal investigator for the Netherlands in the Ariel mission science team. Ariel, unlike the James Webb Space Telescope — will exclusively observe exoplanets, and in particular, their atmospheres.

Miguel obtained her PhD in February 2011 from the Universidad Nacional de La Plata in Argentina, with a thesis entitled “Un modelo determinista para la formación de sistemas planetarios”. She has been affiliated with Leiden University since 2018 and with SRON since 2020.

The Pastor Schmeits Prize is awarded once every three years to one or two astronomers of Dutch nationality or, according to Dutch law, residents of the Netherlands, who have made a scientific contribution of exceptional importance in the preceding five years, and who at the time of publication of the aforementioned contribution have not yet reached the age of forty or have obtained their doctorate no more than 12 years ago.

Yamila Miguel receives the prize for her groundbreaking research in the field of planetary physics. She uniquely combines research on planets in our own solar system with that on exoplanets around other stars. This has yielded important new insights, for example into the structure of gas planets such as Jupiter. Miguel is also a global expert in the field of atmospheric chemistry of so-called super-Earths, a class of planets that do not occur in our own solar system. Her models play a leading role in the interpretation of the latest data from the James Webb Space Telescope.