Astronomers claim strong evidence of alien life, but experts urge caution
Scientists on the hunt for extraterrestrial life just got a new lead.
On a faraway planet, the James Webb Space Telescope picked up signs of molecules that, on Earth, are produced only by living organisms.
But professor Nahum Arav, an astrophysicist in the Virginia Tech College of Science, says we must interpret the results with caution. He answered questions about this fascinating development.
What and where is this exoplanet?
“Any planet that orbits a star other than our Sun is referred to as an exoplanet. Astronomers first discovered the one in question, K2-18b, in 2015. They soon established that it was a promising place to look for life. About eight times as massive as Earth and orbiting a star 124 light years away, the planet sits in the habitable zone of its star, where liquid water can exist on its surface. That zone is sometimes called ‘the goldilocks zone,’ because it’s neither too hot nor too cold, thus just right for liquid water.”
Why do astronomers think this planet might have life?
“In 2023, astronomers used the James Webb Space Telescope to look at K2-18b’s atmosphere in near-infrared light. They found a tantalizing hint of a molecule called dimethyl sulphide. On Earth, this molecule is produced only by living organisms, mainly marine phytoplankton. However, the signs for the molecule on K2-18b were extremely weak. Now that same team observed the planet again with a different instrument from the James Webb Space Telescope, the mid-infrared camera, they have found a stronger signal for the molecule, as well as a possible related molecule called dimethyl disulphide, which is also produced on Earth only by life.”
Why do we need to treat these results with caution?
“It’s worth noting that other scientists are skeptical about the findings, cautioning that there have been false alarms out of K2-18b’s atmosphere before, and that these new observations do not offer convincing evidence that the two molecular signatures are present. Any claim of possible signature of life beyond Earth needs to be verified by other experts analyzing both the same data and hopefully better data sets in the future. However, these new results are certainly worth a closer look.”
About Arav
Nahum Arav is an astrophysics professor in the Virginia Tech Department of Physics where he specializes in determining the influence of super massive black holes on structure formation in the universe.
Schedule an interview
To schedule an interview, contact Mike Allen in the media relations office at mike.allen@vt.edu or 540-400-1700.