What have researchers uncovered in their latest study? Which molecule suggests the potential existence of life?
In what researchers describe as the most compelling evidence to date that we may not be alone in the Universe, scientists have potentially identified dimethyl sulfide—a chemical predominantly linked to life on Earth—in the atmosphere of a distant planet. If this evidence is validated, it would imply that a planet over 100 light-years away contains a substance that, on Earth, is produced solely by plants and microorganisms.
However, before this can be classified as a discovery, numerous questions must be addressed. Scientists need to verify the authenticity of the signal and determine whether it genuinely indicates the presence of life, while also considering various alternative explanations. Regardless of the outcome, these initial findings signify a new chapter in our quest to find life beyond our Solar System.
A potential signal
Employing the James Webb Space Telescope (JWST), a group of researchers examined the atmosphere of the planet K2-18b as it transited in front of its star. This method, known as transmission spectroscopy, enables scientists to analyze the composition of a planet’s atmosphere by observing how light is absorbed by its gases as it travels to Earth. In this instance, the researchers detected signatures that are most plausibly attributed to dimethyl sulfide (DMS), its related compound dimethyl disulfide (DMDS), or possibly both.
Astrobiologists have long sought these molecules, as DMS is exclusively produced by life on Earth, primarily through certain plants and marine microbes that generate a chemical which eventually breaks down into DMS. This makes DMS a highly specific indicator of life, one that is challenging to account for through other means.
The detection of DMS in the atmosphere of K2-18 b would be an incredibly exciting breakthrough, potentially serving as the most compelling evidence of extraterrestrial life discovered outside our Solar System. While telescopes have previously examined the atmospheres of distant planets, none have identified a compound that, on Earth, is exclusively linked to biological processes.
Specifically for K2-18 b, the identification of DMS would validate a long-standing hypothesis advocated by the research team led by Dr. Nikku Madhusudhan at the University of Cambridge. They propose that K2-18 b is a unique type of planet, entirely enveloped by ocean.
If the findings from the JWST are confirmed, it could suggest that these oceans are rich in life.