Scientists have found traces of two chemical compounds in the atmosphere of the distant planet K2-18b, the strongest evidence yet that extraterrestrial life exists.
This is reported by The New York Times.
The massive K2-18b is located outside the solar system — it orbits a star 120 light-years from Earth. The exoplanet was discovered in 2015 by Canadian scientists using data from the Kepler space telescope. K2-18b is a so-called sub-Neptune: a planet larger than an Earth-sized object but smaller than a gas giant like Neptune.
In 2021, a team led by Cambridge University astronomer Nikku Madhusudhan suggested that some sub-Neptunes may have oceans of warm water beneath atmospheres rich in hydrogen, methane, and other carbon compounds. The researchers coined a new term for such bodies, Hycean.
More has been learned since the launch of the James Webb Space Telescope in December 2021. As K2-18b passes near its star, its atmosphere brightens and the gases change color, allowing us to analyze the chemical composition of the planetʼs atmosphere.
In 2023, scientists detected faint signs of dimethyl sulfide (DMS) there, a molecule that is produced on Earth by living organisms, particularly seaweed. It is this substance that gives the sea its characteristic smell.
Last year, K2-18bʼs atmosphere was reanalyzed using another instrument on the Webb telescope. The signal for dimethyl sulfide was even stronger, as was that of a similar molecule, dimethyl disulfide.
It turns out that K2-18b may contain thousands of times more DMS than Earth, suggesting that its oceans could be teeming with life. But the researchers caution that more research is needed to determine whether K2-18b is really a Hycean-type planet or just a hot, rocky giant with magma and a hellish hydrogen atmosphere.
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