Scientists find strongest evidence yet of life on an alien planet

Scientists detect potential biosignatures in the atmosphere of exoplanet K2-18 b, hinting at possible alien life beyond our solar system.

In a potential landmark discovery, scientists using the James Webb Space Telescope have obtained what they call the strongest signs yet of possible life beyond our solar system, detecting in an alien planet's atmosphere the chemical fingerprints of gases that on Earth are produced only by biological processes.

The two gases - dimethyl sulfide, or DMS, and dimethyl disulfide, or DMDS - involved in Webb's observations of the planet named K2-18 b are generated on Earth by living organisms, primarily microbial life such as marine phytoplankton - algae.

This suggests the planet may be teeming with microbial life, the researchers said. They stressed, however, that they are not announcing the discovery of actual living organisms but rather a possible biosignature - an indicator of a biological process - and that the findings should be viewed cautiously, with more observations needed.

Nonetheless, they voiced excitement. These are the first hints of an alien world that is possibly inhabited, said astrophysicist Nikku Madhusudhan of the University of Cambridge's Institute of Astronomy, lead author of the study published in the Astrophysical Journal Letters.

"This is a transformational moment in the search for life beyond the solar system, where we have demonstrated that it is possible to detect biosignatures in potentially habitable planets with current facilities. We have entered the era of observational astrobiology," Mr. Madhusudhan said.

Mr. Madhusudhan noted that there are various efforts underway searching for signs of life in our solar system, including various claims of environments that might be conducive to life in places like Mars, Venus and various icy moons.

K2-18 b is 8.6 times as massive as Earth and has a diameter about 2.6 times as large as our planet.