Forget your umbrella, today’s weather forecast comes not from Earth, but from a blazing rogue planet adrift in the cosmos. SIMP-0136, a lonely world without a parent star, has just delivered one of the most electrifying meteorological revelations in exoplanetary science: fierce auroras, sand-like clouds, and temperature swings that make Earth’s heatwaves look like spring breezes.

Thanks to the ultra-sensitive eyes of the NASA/ESA/CSA James Webb Space Telescope (JWST), astronomers from Trinity College Dublin have turned this drifting brown dwarf into a cosmic weather station. Their findings, published in Astronomy & Astrophysics, offer a vivid glimpse into the atmospheric drama unfolding on SIMP-0136, a world that glows with auroral fire and spins with stormy secrets.

SIMP-0136 isn’t tethered to any star. It’s a rogue planet, a free-floating object roughly 20 light-years away, with a surface temperature soaring above 1,500 °C. Despite its isolation, it’s anything but quiet. As it rotates, JWST captured subtle flickers in brightness, tiny shifts that revealed changes in temperature, chemistry, and cloud cover.

“These are some of the most precise measurements of the atmosphere of any extra-solar object to date,” said Dr. Evert Nasedkin, lead author and postdoctoral fellow at Trinity College Dublin. “And the first time that changes in the atmospheric properties have been directly measured.”

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One of the most dazzling discoveries? SIMP-0136’s auroras. These glowing atmospheric phenomena are akin to Earth’s Northern Lights or Jupiter’s powerful auroral storms, but on a scale that’s truly alien.

The auroras on SIMP-0136 are not just pretty, they’re potent. They heat the planet’s upper atmosphere and contribute to the observed temperature fluctuations. These changes, often less than 5 °C, are linked to rotating storm systems, reminiscent of Jupiter’s Great Red Spot, sweeping across the planet’s face.

If you’re imagining fluffy white clouds, think again. SIMP-0136’s skies are cloaked in clouds made of silicate grains, essentially, floating sand. And unlike Earth’s ever-shifting cloudscape, these clouds appear eerily constant.

“One might expect changes in cloud coverage to lead to changes in the atmosphere,” said Dr. Nasedkin. “Instead, the team found that the cloud coverage was constant over the surface of SIMP-0136.”

Webb found a brown dwarf with auroras

This stability suggests a planet-wide layer of sand-like haze, suspended in a scorching atmosphere, creating a surreal and static sky.

The research marks the debut of Trinity’s new ‘Exo-Aimsir’ group, led by Prof. Johanna Vos, with contributions from PhD candidates Merle Schrader, Madeline Lam, and Cian O’Toole. Their work builds on earlier data from Boston University’s Allison McCarthy, refining the analysis with advanced modeling techniques.

“By applying our state-of-the-art modelling techniques to cutting-edge datasets from JWST, we can begin to piece together the processes that drive weather in worlds beyond our solar system,” said Prof. Vos.

While SIMP-0136 is a brown dwarf, not a true planet, the techniques used to study it pave the way for future explorations of exoplanet atmospheres. Upcoming observatories like the Extremely Large Telescope and the Habitable Worlds Observatory will extend this work to gas giants and rocky planets alike.

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“Understanding these weather processes will be crucial as we continue to discover and characterize exoplanets in the future,” Vos added.

In the end, SIMP-0136 reminds us that even in the cold void between stars, nature finds a way to dazzle. With auroras that burn in the dark, clouds made of sand, and storms that whisper across alien skies, this rogue planet offers a forecast unlike any other, and a glimpse into the wild weather of worlds yet to be explored.

Journal Reference:

E. Nasedkin, M. Schrader, J. M. Vos, B. Biller, B. Burningham, N. B. Cowan, J. K. Faherty, E. Gonzales, M. B. Lam, A. M. McCarthy, P. S. Muirhead, C. O’Toole, M. K. Plummer, G. Suárez, X. Tan, C. Visscher, N. Whiteford, Y. Zhou. The JWST weather report: Retrieving temperature variations, auroral heating, and static cloud coverage on SIMP-0136. Astronomy & Astrophysics, 2025; 702: A1 DOI: 10.1051/0004-6361/202555370