A team of scientists from Cambridge have found new, albeit preliminary, evidence that life could exist on a distant planet called K2-18b, which orbits another star. By studying the planet's atmosphere, they detected molecules that on Earth are only produced by simple organisms. This is what the BBC reports.
This is the second, and much more encouraging, detection of such substances in the planet's atmosphere by the James Webb Space Telescope, but scientists emphasize that more data is needed to confirm these results.
Professor Nikku Madhusudhan, who is leading the research, said they could confirm the signal within one to two years.
"This is the strongest evidence yet there is possibly life out there," he said.
K2-18b is 2.5 times larger than Earth and is located 124 light-years away. The telescope's high power allows it to analyze the composition of the planet's atmosphere using the light passing through it from its red Sun.
Traces of dimethyl sulfide (DMS) and dimethyl disulfide (DMDS) — molecules that are produced by marine phytoplankton and bacteria on Earth — were detected in the atmosphere of K2-18b. According to the professor, the amount of the gas detected is thousands of times higher than Earth's levels.
However, a scientific discovery requires a level of confidence of 99.99999% (five sigma), while the current result is only three sigma (99.7%). However, this is significantly higher than the previous signal from 18 months ago, which had an accuracy of 68%.
Other researchers, including Professor Catherine Heymans, note that even a five-sigma result does not guarantee the biological origin of the gas. After all, it could also have been caused by geological processes.
The scientific community is actively debating not only the nature of these molecules, but also the structure of the planet itself. Some suggest that K2-18b has an ocean of liquid water, although it could also be molten rock. Other studies indicate that the planet may be a mini-gas giant without a solid surface.
Despite all the "buts," Professor Madhusudhan is convinced they are on the right track.
"Decades from now, we may look back at this point in time and recognise it was when the living universe came within reach," he added.