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Looking to Clouds in the Search for Habitable Exoplanets

What can clouds on distant planets tell us in our search for habitable planets? How could the next generation of telescopes amplify our understanding of exoplanet atmospheres?

These are the big questions Dr. Thaddeus Komacek, a 2018 51 Pegasi b Fellowship alumnus, seeks to answer. Through the use of 3D simulations, Thaddeus explores the nature of clouds and climate on a broad range of exoplanets.

Dr. Thaddeus Komacek

The Heising-Simons Foundation caught up with Thaddeus to see where his research has taken him as an assistant professor of astronomy at the University of Maryland, College Park.


Tell us about your current studies.

My work today very much follows on the threads of my 51 Pegasi b Fellowship project. Then, like now, I was examining exoplanet atmospheres through cloud behavior simulations—because we know the underlying mechanics of these planets can help guide and make sense of observations, including those of newer space-based telescopes.

Only now, my work involves more than myself and a postdoc advisor. I’m very lucky to have a whole group of students along for the ride. As in my fellowship, our research is focused on the atmospheric circulation of planets, split between studying planets we can characterize with current observatories and figuring out how cloud cover could impact the detectability of biosignatures in exoplanets we might discover in future space missions.

Any specific projects you’d like to highlight?

Sure, there are two big ones I’d mention. First, we’re conducting a large suite of numerical simulations that include cloud microphysics in order to understand differences in cloud cover on the night sides of Hot and ultra-Hot Jupiter-sized exoplanets. This stems from an inference based on recent Spitzer Space Telescope observations and may inform how we can interpret these as well as observations from JWST.

The other project grew more directly out of my 51 Pegasi b Fellowship work. For this one, we’re studying whether tropical cyclones or hurricanes occur on rocky exoplanets orbiting M dwarf stars. And if so, we want to find out how common they are. Scientists have predicted that these types of storms would be likely in specific regions of these exoplanets. We’re following up by conducting simulations at a high enough resolution to include hurricanes.

How did the 51 Pegasi b Fellowship help set you up to do this work?

The Fellowship gave me the time and independence required to learn a whole new modeling toolset for rocky, Earth-like planets. It also gave me the opportunity to interact with experts beyond my immediate field and learn new things. I did my fellowship at the University of Chicago, where I was able to connect with Earth climate scientists and oceanographers to learn the tricks of the trade and details important to their studies. In planetary science, we’re typically thinking about big-picture things, but with Earth’s climate, the small-scale effects really matter—and we have such good data to match.

When you look back at your Fellowship project, what insights or achievements were most significant for you?

As a theorist and a modeler, everything I do is effectively irrelevant unless it can be tested by real-world data. Spending time with Earth scientists and understanding these interdisciplinary connections helped me realize that I want to do science that is impactful to the community as a whole and to the public at large. I’m excited to interpret and inform observations with JWST that we can share with a broader audience.

As for an achievement, we predicted that key habitability indicators like water vapor would be hidden by clouds while carbon dioxide should be clearly detectable if it’s abundant in a thick exoplanet atmosphere. This prediction could be directly tested with JWST once we better understand its capabilities around detecting atmospheres on rocky planets.

When you think about the future of the field and what’s next for planetary astronomy, what role do you hope to play?

I think the planetary science field is moving from a set of highly competitive independent groups to becoming more collaborative and networked. This is evident through early JWST observations where hundreds of exoplanet scientists are collaborating on the first results. I hope to become a leader in larger collaborations working to solve big-picture questions, especially in the coming decades as the Habitable Worlds Observatory (HWO) and The Large Interferometer For Exoplanets (LIFE) initiatives are launched.

I also want to continue pushing boundaries toward developing unified simulation platforms that could be applied to all types of exoplanets. These models would be flexible, user-friendly, and accessible. Anyone could grab the software and use it to simulate the climate of their favorite exoplanet or fantasy world. This would enhance public engagement and create a framework that matches the broad range of exoplanets now accessible through JWST.

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