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- SIMP 0136 is a giant planet<\/strong> much more massive than Jupiter. It is rogue, meaning it doesn\u2019t orbit a star. Instead, it drifts alone in space.<\/li>\n
- Astronomers observed huge auroras<\/strong> \u2013 similar to Earth\u2019s northern lights \u2013 when they observed the rogue planet using the James Webb\u00a0Space\u00a0Telescope.<\/li>\n
- Webb also observed a surprising lack of variability<\/strong> in the cloud cover of the planet. And Webb tracked changes in the searing temperatures of SIMP 0136.<\/li>\n<\/ul>\n
Powerful auroras on rogue planet<\/h3>\n
Auroras \u2013 also known as the southern or northern lights on Earth \u2013 are common on planets in our solar system. But what about planets elsewhere, including rogue planets? Rogue planets are planets don\u2019t orbit any stars; instead, they float freely in interstellar space. Researchers at Trinity College Dublin in Ireland observed the rogue planet SIMP 0136, a super-Jupiter about 20 light-years away, using the James Webb Space Telescope (JWST). <\/p>\n
They tracked changes in the planet\u2019s temperature, clouds and chemistry. And on September 26, 2025, they said they saw strong auroras in the atmosphere of the wandering planet. The auroras on SIMP 0136 are similar to those on Earth or the more powerful auroral displays on Jupiter.<\/p>\n
Astronomers first discovered the auroras on SIMP 0136 back in 2018, using the Karl G. Jansky Very Large Array (VLA). But now the Webb telescope can take an even closer look at them.<\/p>\n
The researchers published their peer-reviewed findings in Astronomy & Astrophysics<\/em> on September 26, 2025.<\/p>\n
Meet SIMP 0136<\/h3>\n
SIMP 0136 is a rogue planet, one that isn\u2019t gravitationally bound to a star. It is huge, about 13 times more massive than Jupiter and 1.2 times the radius. It is fairly close by, only about 20 light-years away. SIMP 0136 is hot<\/em>, at about 2,700 degrees Fahrenheit (1,500 degrees Celsius).<\/p>\n
Some astronomers classify SIMP 0136 as a brown dwarf, rather than a planet. Brown dwarfs are typically larger than the largest gas giant planets but smaller than the smallest stars.<\/p>\n
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? It’s paper day! Today I’m sharing the latest in a series of papers looking at the weather on other worlds, in this case bringing you the weather report from a nearby T-dwarf, SIMP-0136. ?? to follow\u2026<\/p>\n
\u2014 Evert Nasedkin (@evertnasedkin.bsky.social) 2025-09-26T09:05:15.405Z<\/p>\n<\/blockquote>\n
New analysis of SIMP 0136\u2019s atmosphere<\/h3>\n
The astronomers were observing SIMP 0136 to learn more about its atmosphere, temperature and chemistry. Evert Nasedkin at Trinity\u2019s School of Physics is the lead author of the new study. He said:<\/p>\n
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These are some of the most precise measurements of the atmosphere of any extra-solar object to date, and the first time that changes in the atmospheric properties have been directly measured.<\/p>\n
And at over 1,500 degrees Celsius, SIMP-0136 makes this summer\u2019s heat wave look mild. The precise observations we made meant we could accurately record temperature changes smaller than 5 degrees Celsius. These changes in temperature were related to subtle changes in the chemical composition of this free-floating planet, which is suggestive of storms \u2013 similar to Jupiter\u2019s Great Red Spot \u2013 rotating into view\u2026.<\/p>\n
Different wavelengths of light are related to different atmospheric features. Similar to observing the changes in color over the surface of the Earth, the changes in the color of SIMP 0136 are driven by changes in the atmospheric properties. So by using cutting-edge models, we could infer the temperature of the atmosphere, the chemical composition, and the position of the clouds.<\/p>\n<\/blockquote>\n
![\"Auroral](\"https:\/\/earthsky.org\/upl\/2023\/11\/aurora-Joel-Weatherly-Edmonton-Alberta-CN-nov12-2023-213-am-e1699791902593.jpg\")
View at EarthSky Community Photos. | Joel Weatherly in Edmonton, Alberta, Canada, caught the northern lights on November 12, 2023. Thank you, Joel! Other planets in our solar system and even rogue planets also have auroras.<\/figcaption><\/figure>\n Other surprises on SIMP 0136<\/h3>\n
There is also heating in the stratosphere of SIMP 0136, similar to heating from auroras on Earth and other planets. Notable, however, the researchers haven\u2019t yet been able to connect the heating on SIMP 0136 directly to its auroras. The paper says:<\/p>\n
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SIMP-0136 is known to emit pulsed radio signals, which is attributed to the large scale currents generated by electrons flowing along magnetic field lines. These electrons interact with the atmosphere, releasing energy and forming auroras. While our retrievals find heating in the stratosphere of SIMP 0136, it is challenging to directly attribute this to heating from auroral processes: there is still no direct evidence for UV or IR auroral emission in SIMP 0136.<\/p>\n<\/blockquote>\n
![\"Smiling](\"https:\/\/earthsky.org\/upl\/2025\/09\/Evert-Nasedkin-Trinity-College-Dublin.jpeg\")
Evert Nasedkin at Trinity College Dublin in Ireland is the lead author of the new study of SIMP 0136. Image via Evert Nasedkin\/ GitHub.<\/figcaption><\/figure>\n The observations also revealed an unexpected lack of variability in the planet\u2019s cloud cover. Indeed, the cloud coverage was constant. In addition, those clouds are unlike any on Earth. Instead of water, they are composed of tiny grains of silicate. That\u2019s similar to the composition of grains of sand on a beach.<\/p>\n
Weather on other worlds<\/h3>\n
The modeling techniques used for SIMP 0136 can also be applied to other exoplanets as well. Johanna Vos at Trinity\u2019s School of Physics said:<\/p>\n
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This work is exciting because it shows that 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. Understanding these weather processes will be crucial as we continue to discover and characterize exoplanets in the future.<\/p>\n
While for now these types of spectroscopic variability observations are limited to isolated brown dwarfs, like this one, future observations with the Extremely Large Telescope and eventually the Habitable Worlds Observatory will enable the study of the atmospheric dynamics of exoplanets, from Jupiter-like gas giants to rocky worlds.<\/p>\n<\/blockquote>\n
Bottom line: Using the Webb space telescope, astronomers have observed auroras on rogue planet SIMP 0136. The giant starless world is about 20 light-years away from Earth.<\/p>\n
Source: The JWST weather report: Retrieving temperature variations, auroral heating, and static cloud coverage on SIMP-0136<\/p>\n
Via Trinity College Dublin<\/p>\n
Read more: Enormous rogue super-Jupiter is a surprisingly complex world<\/p>\n
Read more: Astronomers find weird rogue world with wild auroras<\/p>\n
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\n - Astronomers observed huge auroras<\/strong> \u2013 similar to Earth\u2019s northern lights \u2013 when they observed the rogue planet using the James Webb\u00a0Space\u00a0Telescope.<\/li>\n