A fiery aurora reveals a weather-rich rogue planet
In a striking departure from typical planet weather reports, astronomers studying the lone world SIMP-0136 — a rogue planet that orbits nothing but the darkness of interstellar space — have detected Northern Lights–style auroras and a surprisingly dynamic atmosphere. The observations come from the NASA/ESA/CSA James Webb Space Telescope (JWST), and they offer a rare window into the weather of an extrasolar world that does not orbit a sun.
How JWST captured alien weather
Thanks to JWST’s exceptional sensitivity, the team could monitor minute brightness changes as SIMP-0136 rotated. Those light-variations map shifts in temperature, cloud coverage, and chemical composition across the planet’s surface. The results push the envelope of exoplanetary meteorology, with measurements precise enough to resolve temperature swings smaller than 5 °C even as the planet boasted searing daytime temperatures around 1,500 °C. Such precision enables scientists to connect subtle atmospheric changes to the chemistry occurring high in the planet’s atmosphere.
Temperature, chemistry and a hint of storms
Among the most surprising findings is the link between tiny temperature fluctuations and shifts in atmospheric chemistry, a signpost for storm-like activity sweeping across SIMP-0136’s atmosphere. The team notes that these dynamic processes may resemble the large, long-lived storms seen on gas giants in our solar system, rotating into view as the planet turns. Yet on this world, the heat and atmospheric chemistry unfold at temperatures and pressures far removed from Earth’s climate, underscoring the diversity of weather found in the galaxy.
Clouds that look like sand on a distant beach
Another unexpected result was the constancy of cloud cover over the planet’s surface. Unlike a sky where cloud patches ebb and flow, SIMP-0136’s clouds remained remarkably uniform. At these extreme temperatures, the clouds are not water-based; they are composed of silicate grains, akin to beach sand. Such mineral clouds have unique optical properties that shape how light escapes the planet’s atmosphere and how scientists read its rainbow of spectral fingerprints.
The Exo-Aimsir group leads the way
These measurements mark the first publication from Trinity College Dublin’s new Exo-Aimsir group, led by Professor Johanna Vos in the School of Physics. The study builds on earlier work by Allison McCarthy’s team at Boston University, but the reanalysis with cutting-edge models has unlocked additional details about the atmosphere. The lead author, Dr. Evert Nasedkin, emphasized that different wavelengths reveal different atmospheric features, enabling researchers to infer temperature, chemistry, and cloud position with remarkable fidelity. The project also highlights the contributions of group members including PhD candidates Merle Schrader, Madeline Lam, and Cian O’Toole.
Why this matters—and what comes next
Prof. Vos highlighted the broader significance: by applying state-of-the-art modeling to JWST datasets, scientists are beginning to piece together the processes that drive weather in worlds beyond our solar system. Understanding these atmospheric dynamics is crucial as researchers continue to discover and characterize exoplanets in the future. While spectroscopic variability studies have so far been limited to isolated brown dwarfs like SIMP-0136, upcoming facilities such as the Extremely Large Telescope (ELT) and, eventually, the Habitable Worlds Observatory, will extend these insights to a wider range of exoplanets — from Jupiter-like gas giants to rocky worlds that might bear closer resemblance to Earth.
A glimpse into a future of exoplanet weather studies
In the long term, the ability to observe how weather evolves across exoplanets will help astronomers understand how planetary atmospheres function under different stellar and environmental conditions. SIMP-0136 serves as a compelling test case: a scorching, starless world where auroras and mineral clouds illuminate the upper atmosphere, revealing a weather system that operates under physics unlike anything seen in our solar system. As telescope technology advances, researchers anticipate applying similar techniques to a broader class of distant worlds, shedding light on the climates of planets both far and near.
