A world 20 light-years away reveals surprisingly organized, Jupiter-like weather

Scientists from Trinity College Dublin have developed a way to unravel changing weather patterns on distant worlds. Using this approach, they discovered that the weather on a well-studied brown dwarf, SIMP 0136, previously linked to northern lights-like phenomena, is largely shaped by just two dominant processes: changes in temperature and the vertical structure of its clouds.

Using observations from NASA’s James Webb Space Telescope (JWST), the team applied a statistical technique called principal component analysis (PCA) to track how the object’s light changes as it rotates. PCA simplifies complex data by identifying the main patterns that change together across observations.

In this study, those dominant patterns are linked to weather-related changes in the brown dwarf’s atmosphere, allowing researchers to distinguish them from smaller fluctuations and random “noise” in the data.

Rather than relying on complex assumptions about its atmosphere, the method allowed the researchers to identify the key physical processes directly from the data. The data showed minute changes in the brightness of the planetary-mass object as it rotated, which were made detectable by the exceptional sensitivity of JWST’s instruments.

Key insights

The vast majority of the atmospheric variability could be explained by only two dominant components, consistent with changes in temperature and the vertical structure of clouds.

This insight reveals an atmosphere whose observed changes can be explained by three recurring weather states that rotate in and out of view, producing a patchwork of hotter, thinner-cloud regions alongside cooler areas with thicker, vertically extended clouds.

The new research, published in the journal Astronomy & Astrophysics, suggests that, despite its apparent complexity, the atmosphere of SIMP 0136 behaves in a remarkably organized way rather than reorganizing randomly.

The brown dwarf is a world larger and hotter than a gas giant planet but not massive enough to shine like a star. Its atmosphere is dominated by huge, fast-changing cloud systems. In that sense, it is less like Earth and more like an extreme version of Jupiter, with planet-sized weather patterns constantly reshaping what astronomers see.

“We also discovered that these drivers of the weather patterns on SIMP 0136 persist over time, even as the detailed appearance of the atmosphere evolves over more than a dozen rotations,” said first author Merle Schrader, a Ph.D. candidate in Trinity’s School of Physics.

“In relative terms, SIMP 0136 is one of the easier brown dwarfs for us to capture high-quality data from. These data have been studied before by established methods, allowing us to compare some of the results from this new technique to what we already know about this object.

The technique has also helped us develop a better understanding of what drives the weather on this faraway world and how these weather patterns interact and coexist, but perhaps even more importantly, it shows how this approach can be further refined and applied to other, less well-known brown dwarfs in different parts of space.”

There is a personal connection for Schrader and her test subject, SIMP 0136, which is 20 light-years (about 189 trillion km, 117 trillion miles) from Earth. Some quick math confirms that the light that provided the data analyzed in this paper, which was first observed by JWST in 2023, was emitted the year Schrader was born.

“Light travels at around 300,000 km/s but, even at that speed, it took two decades to reach us, peering through the JWST lenses,” she said.

“When you consider that light takes just over a second to reach the moon after leaving Earth, that gives a sense of how far away SIMP 0136 is and how incredible astrophysical progress has been. I think it’s amazing that we have been able to discern the intimate weather patterns of a distant world and map their interactions from our cozy little corner of the universe, when all we observe directly of these objects is a single pixel spread across the light spectrum.”

What is the potential impact of this research?

Understanding the weather on objects like SIMP 0136 is important because brown dwarfs provide a unique laboratory for studying the physics of giant exoplanet atmospheres. Unlike most exoplanets, they can be observed directly, allowing astronomers to test ideas about cloud formation, atmospheric circulation and heat transport under extreme conditions.

Johanna Vos, an associate professor in Trinity’s School of Physics, said, “Our findings will transform how astronomers analyze future JWST observations. Since our approach rapidly identifies the dominant components of the atmosphere, it offers an efficient first step before we begin computationally intensive modeling.

“Applying this technique to a wide range of brown dwarfs and giant exoplanets will help us better understand the diverse weather systems that shape worlds far beyond our solar system.”

Even more broadly, scientists are interested in better understanding weather patterns on distant planets because they reveal a lot about their atmospheres and chemical composition, an important step toward identifying the kinds of worlds where life could potentially exist.

Who’s behind this story?

Swati Mestri

Swati Mestri holds a bachelor’s degree in Electronics Engineering and has worked as a content editor since 2019. She has experience editing research documents across technology, health care, and materials science, and has a particular interest in technology and space.

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Robert Egan

Bachelor’s in mathematical biology, Master’s in creative writing. Well-traveled with unique perspectives on science and language.

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