- EXPLORE FURTHER: Enigmatic Martian formations 'suggest existence of life on the Red Planet'
An ocean-filled planet far away, brimming with living creatures.
This could be the most probable interpretation of a recent finding by researchers who claim to have uncovered the strongest evidence so far of extraterrestrial life. solar system .
Using data from the James Webb The astronomers, spearheaded by, utilizing the James Webb Space Telescope (JWST), University of Cambridge have pinpointed the chemical signatures of dimethyl sulfide (DMS) and dimethyl disulfide (DMDS) — compounds that suggest the presence of living organisms.
On our planet, these molecules are exclusively created by living entities – mainly microscopic beings like oceanic phytoplankton.
These molecules have been found in the atmosphere of exoplanet K2-18b, situated approximately 124 light-years away from us in the constellation Leo.
It revolves around a red dwarf star within the so-called 'habitable zone,' which is deemed the most promising area for discovering planets capable of supporting life.
K2-18b has a diameter 2.6 times greater and a mass 8.6 times more than Earth’s, and specialists think it is probably enveloped in an ocean — thus categorizing it as a 'Hycean planet.'
The world’s temperature resembles Earth's, yet it orbits so near to its star that a single year there completes in merely 33 days.
Previous observations detected methane and carbon dioxide in its atmosphere — marking the first instance where carbon-based compounds were found on an exoplanet located within the habitable zone.
Currently, an examination of fresh data has revealed substances that, according to what scientists know, are generated exclusively by living entities.
The levels of DMS and DMDS in K2-18b's atmosphere vary significantly from those on Earth, where they typically fall below one part per billion by volume.
On K2-18b, they are believed to be thousands of times more powerful — exceeding 10 parts per million.
Professor Nikku Madhusudhan, who leads the research, hails from the Institute of Astronomy at Cambridge.
'Theoretical studies previously suggested that high concentrations of sulfur-containing gases such as DMS and DMDS could be present on Hycean planets,' he explained.
'Now that we have seen it, just as anticipated.'
Based on all the information we have about this planet, a Hycean world featuring an ocean brimming with life aligns most closely with the evidence we possess.
He mentioned that although the findings are thrilling, it’s crucial to gather additional information prior to asserting that life exists on another planet.
Even though he remains guardedly positive, unidentified chemical reactions occurring on K2-18b might explain these discoveries.
Additional observations from the JWST are required to ensure their findings aren't merely due to random variation.
His group is likewise planning to carry out additional tests to find out if DMS and DMDS can be generated abiotically at the levels presently observed.
'Years into the future, we might reflect upon this moment as the turning point when access to a living universe became possible,' stated Professor Madhusudhan.
This might be the turning point where we can finally address the basic question of whether we are solitary beings in the cosmos.
To figure out what gases make up distant exoplanets' atmospheres, scientists examine the light coming from their host stars when these planets pass in front of them during transit.
When K2-18b moves across the star, JWST observes a decrease in the star’s luminosity, with a minuscule portion of light filtering through the exoplanet’s atmosphere en route to our planet.
Some of the starlight passing through the planet’s atmosphere gets absorbed, leaving distinct marks within the stellar spectrum. Astronomers analyze these markings to identify the various gases present in the exoplanet’s atmosphere.
In last year's observations, JWST picked up faint indications of 'additional activity occurring' on K2-18b along with finding methane and carbon dioxide.
'Last time, we weren’t certain if the signal we detected was because of DMS, but even the possibility excited us enough to observe again with JWST using a different instrument,' Professor Madhusudhan clarified.
Initially, the provisional hypothesis about DMS was established through observations with JWST’s NIRISS (Near-Infrared Imager and Slitless Spectrometer), along with data from NIRSpec (Near-Infrared Spectrograph). These tools collectively span the near-infrared spectrum between 0.8 to 5 microns.
The recently independent observation utilized JWST's MIRI (Mid-Infrared Instrument) for measurements in the mid-infrared spectrum (6-12 microns).
Professor Madhusudhan stated, 'This represents a separate strand of proof obtained through a distinct apparatus from our earlier efforts and within a varying spectrum of light, ensuring no duplication with prior measurements.'
'The transmission was robust and distinct.'
Måns Holmgren, who co-authored the study and works as a researcher at the Space Telescope Science Institute in Baltimore, USA, commented: "Seeing the results come through consistently across multiple independent analyses and rigorous testing was simply astounding."
DMs and DMDS belong to the same chemical group, and both are expected to serve as indicators of biological activity.
Although both molecules exhibit overlapping spectral characteristics within the observed wavelength range, additional observations will be beneficial in distinguishing them from one another.
"Our research serves as the foundation for subsequent inquiries required to validate and elucidate the significance of these intriguing discoveries," stated co-author Savvas Constantinou, who is affiliated with Cambridge's Institute of Astronomy as well.
The team states that their findings have achieved a 'three-sigma' level of statistical significance, indicating that there is only a 0.3 percent likelihood that these observations happened randomly.
To achieve the recognised status of a scientific discovery, the observations must surpass the five-sigma threshold, indicating less than a 0.00006 percent likelihood that they happened randomly.
They indicated that approximately 16 to 24 hours of additional observing time with the JWST could assist them in achieving the crucial five-sigma significance level.
The finding was documented in the publication The Astrophysical Journal Letters.
A few weeks ago, researchers disclosed the discovery of organic molecules of 'unprecedented size' on Mars, providing additional proof that life might have existed there in the past.
Specialists discovered lengthy carbon chains with up to 12 linked atoms in chunks of ancient Martian rocks that are billions of years old.
These carbon-based compounds – the most extensive ones detected up until now – might stem from fatty acids, which form the foundation of fats and oils and are produced on Earth via biological processes.
Scientists stated that the finding is of 'great significance' in the quest for possible indicators of life.
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