Strongest evidence of life yet found on planet beyond solar system, scientists say

Scientists have found what they are calling the strongest sign yet of possible life beyond our solar system after detecting the chemical footprint of gases in an alien planet’s atmosphere that on Earth are only produced by living organisms.

Using the James Webb Space Telescope, scientists found traces of two gases – dimethyl sulfide (DMS) and dimethyl disulfide (DMDS) – on a planet named K2-18 b.

On Earth, those gases are generated primarily by living organisms including algae, suggesting K2-18 b could be teeming with microbial life.

Researchers have stressed the findings are not an announcement of the discovery of actual living organisms, but rather an indicator of a biological process.

K2-18 b, located about 124 light-years from Earth in the constellation Leo, is 8.6 times as massive as Earth and has a diameter about 2.6 times as large as our planet.

It orbits in the “habitable zone” – a distance where liquid water, a key ingredient for life, can exist on a planetary surface.

Nikku Madhusudhan of the University of Cambridge’s Institute of Astronomy, said it was a “transformational moment in the search for life beyond the solar system”.

“We have entered the era of observational astrobiology,” Professor Madhusudhan said.

Earlier observations by Webb, which was launched in 2021 and became operational in 2022, had identified methane and carbon dioxide in K2-18 b’s atmosphere, the first time that carbon-based molecules were discovered in the atmosphere of an exoplanet in a star’s habitable zone.

“The only scenario that currently explains all the data obtained so far from JWST (James Webb Space Telescope), including the past and present observations, is one where K2-18 b is a hycean world teeming with life,” Professor Madhusudhan said.

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Other scientists not involved in the study urged caution.

“The rich data from K2-18 b make it a tantalising world,” said Christopher Glein, principal scientist at the Space Science Division of the Southwest Research Institute in Texas.

“These latest data are a valuable contribution to our understanding.

“Yet, we must be very careful to test the data as thoroughly as possible. I look forward to seeing additional, independent work on the data analysis starting as soon as next week.”