Possible Biosignature Detected on Distant Exoplanet Sparks Excitement—and Caution

[kevinaggner]

Astronomers have detected what may be the most compelling evidence yet of a potential biosignature beyond our solar system. Using data from the James Webb Space Telescope (JWST), a research team led by the University of Cambridge has identified the spectral fingerprints of dimethyl sulfide (DMS) and/or dimethyl disulfide (DMDS) in the atmosphere of the exoplanet K2-18b, which orbits within the habitable zone of its star.

On Earth, both DMS and DMDS are exclusively produced by life—primarily by marine microorganisms such as phytoplankton. While it's possible that a previously unknown chemical process could be responsible for these molecules on K2-18b, the finding represents the strongest indication yet that life might exist on a planet outside our solar system.

The observations have reached a statistical confidence of three sigma, meaning there's only a 0.3% chance the signal is a fluke. However, the widely accepted threshold for a scientific discovery is five sigma, which would reduce that probability to just 0.00006%. The researchers estimate that an additional 16 to 24 hours of JWST observation time could help reach this critical milestone. Their findings are detailed in The Astrophysical Journal Letters.

K2-18b, located 124 light-years away in the constellation Leo, is about 8.6 times the mass of Earth and 2.6 times larger. Previous studies have already revealed methane and carbon dioxide in its atmosphere—marking the first detection of carbon-bearing molecules on a habitable-zone exoplanet. These earlier findings supported the idea that K2-18b is a "Hycean" world—one covered by a vast ocean beneath a hydrogen-rich atmosphere.

A weaker signal from those earlier observations hinted at the presence of DMS, prompting the team to conduct follow-up studies using a different instrument aboard JWST. “We weren’t sure at the time if the signal was really DMS, but it was compelling enough for us to investigate further,” said Professor Nikku Madhusudhan, lead author of the study from Cambridge's Institute of Astronomy.

To analyze exoplanet atmospheres, astronomers examine starlight passing through the atmosphere as the planet transits in front of its star. Molecules in the atmosphere absorb specific wavelengths of light, creating spectral signatures that reveal the atmosphere’s composition.

The previous DMS detection came from JWST's near-infrared instruments, NIRISS and NIRSpec, which scan the 0.8–5 micron wavelength range. The new detection, made using JWST’s MIRI (Mid-Infrared Instrument), spans 6–12 microns and offers a completely independent confirmation.

“This is a separate line of evidence, with a different instrument and a non-overlapping wavelength range, and yet the signal is still strong and consistent,” said Madhusudhan. “That was an incredible moment.”

Co-author Måns Holmberg of the Space Telescope Science Institute described the consistency across independent analyses as “an incredible realization.”

https://www.consolefun.fr/forum/viewtopic.php?t=45887
https://www.consolefun.fr/forum/viewtopic.php?t=45886
https://www.consolefun.fr/forum/viewtopic.php?t=45885
https://www.consolefun.fr/forum/viewtopic.php?t=45882
https://www.consolefun.fr/forum/viewtopic.php?t=45880
https://sundren.games/forum/main-forum/ ... kins-2025/
https://sundren.games/forum/main-forum/ ... date-2025/
https://sundren.games/forum/main-forum/ ... date-2025/
https://sundren.games/forum/main-forum/ ... date-2025/
https://sundren.games/forum/main-forum/ ... ney-coins/
https://sundren.games/forum/main-forum/ ... ted-money/
https://sundren.games/forum/main-forum/ ... -unlocked/
https://sundren.games/forum/main-forum/ ... y-updated/
https://sundren.games/forum/main-forum/ ... ted-money/
https://sundren.games/forum/main-forum/ ... date-2025/
https://sundren.games/forum/main-forum/ ... oney-gold/
https://sundren.games/forum/main-forum/ ... test-2025/
https://sundren.games/forum/main-forum/ ... oney-gold/
https://sundren.games/forum/main-forum/ ... ted-money/
https://sundren.games/forum/main-forum/ ... date-2025/
https://sundren.games/forum/main-forum/ ... -all-cars/
https://sundren.games/forum/main-forum/ ... -shopping/
https://sundren.games/forum/main-forum/ ... -all-cars/
https://sundren.games/forum/main-forum/ ... -shopping/
https://sundren.games/forum/main-forum/ ... kins-2025/
https://sundren.games/forum/main-forum/ ... ocked-all/
https://sundren.games/forum/main-forum/ ... all-skins/
https://sundren.games/forum/main-forum/ ... ted-money/
https://sundren.games/forum/main-forum/ ... sion-2025/
https://sundren.games/forum/main-forum/ ... date-2025/
https://sundren.games/forum/main-forum/ ... -all-cars/
https://sundren.games/forum/main-forum/ ... date-2025/
https://sundren.games/forum/main-forum/ ... ll-busses/
https://sundren.games/forum/main-forum/ ... sion-2025/
https://sundren.games/forum/main-forum/ ... -all-cars/
https://sundren.games/forum/main-forum/ ... all-skins/
https://sundren.games/forum/main-forum/ ... oney-2025/
https://sundren.games/forum/main-forum/ ... -shopping/
https://sundren.games/forum/main-forum/ ... -diamonds/
https://sundren.games/forum/main-forum/ ... oney-gold/
https://sundren.games/forum/main-forum/ ... el-max-99/
https://sundren.games/forum/main-forum/ ... -shopping/
https://sundren.games/forum/main-forum/ ... -all-cars/
https://sundren.games/forum/main-forum/ ... -shopping/
https://sundren.games/forum/main-forum/ ... ash-coins/
https://sundren.games/forum/main-forum/ ... ruck-2024/
https://sundren.games/forum/main-forum/ ... all-items/
https://www.thekgh.org/forum/idle-miner ... cash-coins
https://forum.beloader.com/forum.php?mo ... d&tid=3258
https://forum.beloader.com/forum.php?mo ... d&tid=3257
https://forum.beloader.com/forum.php?mo ... d&tid=3255
https://forum.beloader.com/forum.php?mo ... d&tid=3254
https://forum.beloader.com/forum.php?mo ... d&tid=3253
https://forum.beloader.com/forum.php?mo ... d&tid=3252
https://forum.beloader.com/forum.php?mo ... d&tid=3251
https://forum.beloader.com/forum.php?mo ... d&tid=3241
https://forum.beloader.com/forum.php?mo ... d&tid=3240
https://forum.beloader.com/forum.php?mo ... d&tid=3239
https://forum.beloader.com/forum.php?mo ... d&tid=3238
https://forum.beloader.com/forum.php?mo ... d&tid=3237
https://forum.beloader.com/forum.php?mo ... d&tid=3236
https://forum.beloader.com/forum.php?mo ... d&tid=3235
https://forum.beloader.com/forum.php?mo ... d&tid=3234
https://forum.beloader.com/forum.php?mo ... d&tid=3233
https://forum.beloader.com/forum.php?mo ... d&tid=3231
https://forum.beloader.com/forum.php?mo ... d&tid=3230
https://forum.beloader.com/forum.php?mo ... d&tid=3229
https://forum.beloader.com/forum.php?mo ... d&tid=3228
https://forum.beloader.com/forum.php?mo ... d&tid=3227
https://forum.beloader.com/forum.php?mo ... d&tid=3226
https://forum.beloader.com/forum.php?mo ... d&tid=3225
https://forum.beloader.com/forum.php?mo ... d&tid=3224
https://forum.beloader.com/forum.php?mo ... d&tid=3222
https://forum.beloader.com/forum.php?mo ... d&tid=3221
https://forum.beloader.com/forum.php?mo ... d&tid=3220
https://forum.beloader.com/forum.php?mo ... d&tid=3219
https://forum.beloader.com/forum.php?mo ... d&tid=3218
https://forum.beloader.com/forum.php?mo ... d&tid=3217
https://forum.beloader.com/forum.php?mo ... d&tid=3216
https://forum.beloader.com/forum.php?mo ... d&tid=3214
https://forum.beloader.com/forum.php?mo ... d&tid=3209
https://forum.beloader.com/forum.php?mo ... d&tid=3208
https://forum.beloader.com/forum.php?mo ... d&tid=3207



While both DMS and DMDS are considered potential biosignatures, their spectral features can overlap, and further observations will be needed to distinguish between them. Intriguingly, the concentrations observed on K2-18b are dramatically higher than on Earth—on the order of 10 parts per million, compared to less than one part per billion here.

“These elevated levels are in line with previous predictions for Hycean worlds,” said Madhusudhan. “Given the data, the best-fit scenario remains an ocean-covered planet with abundant life in its waters.”

Still, the research team stresses the need for caution. While the data are compelling, the possibility remains that unknown chemical processes could explain the presence of DMS or DMDS. More observations are needed before making any definitive claims about life beyond Earth.

“I’m cautiously optimistic,” said Madhusudhan. “We’re seeing what we predicted, and it’s incredibly exciting—but we have to be rigorous. This could be life, or it could be chemistry we just haven’t discovered yet.”