A team of scientists said Wednesday they have found the strongest signs yet of possible life on a massive planet beyond our solar system. 

"What we are finding at this point are hints of possible biological activity outside the solar system," said Nikku Madhusudhan, an astrophysicist at Cambridge University.

Madhusudhan told a press conference that detecting chemical fingerprints of gases, which on Earth are produced only by biological processes, was the first hint of a potentially inhabited alien world.

"This is a revolutionary moment," he told reporters at a press conference to mark a potentially life-changing discovery using the James Webb Space Telescope.

Strongest sign of extraterrestrial life on K2-18 b 

The team was also quick to urge caution, saying that they were not announcing the discovery of actual living organisms and more observations were needed to determine exactly what they were seeing.

The study, which was published in the Astrophysical Journal Letters, said researchers instead discovered a possible biosignature or an indicator of a biological process on a planet that orbits a star 120 light-years from Earth. 

Microbial life on a planet orbiting a star 120 light-years away

This potential evidence of microbial life is on a planet named K2-18 b, which is about 8.6 times as massive as Earth and has a diameter about 2.6 times as large as our planet.

The planet lies 120 light-years away and scientists have previously revealed the presence of carbon-bearing molecules including methane and carbon dioxide (carbon-based molecules are the building blocks of life) on the exoplanet, which means a planet that orbits stars outside of our solar system.

Previous studies have suggested that K2-18 b could be a Hycean exoplanet, one that has the potential to possess a hydrogen-rich atmosphere and a water ocean-covered surface.

Scientists urge patience in search for life beyond Earth

Christopher Glein, the principal scientist at the Space Science Division of the Southwest Research Institute in Texas, describes K2-18 b as "a tantalizing world" but warns that the scientific community ought to be "careful to test the data as thoroughly as possible."

Sara Seager, a professor of planetary science at MIT, urges patience, pointing to an instance when earlier claims of water vapor in K2-18 b's atmosphere turned out to be a different gas.

Edited by: Roshni Majumdar