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K2-18b, which orbits a star 124 light-years from Earth is a “Hycean planet” — meaning it’s home to an abundance of a life.
A handout artist's impression released on April 17, 2025 by N. Madhusudhan/University of Cambridge, shows the K2-18b super-Earth, a hycean world, such as exoplanet K2-18b which astronomers say they have found the strongest yet 'hints' of the life outside this solar system. Picture: Handout / University of Cambridge / AFP
The proverbial question of whether we are alone in the universe has been answered after scientists found new but tentative evidence that a faraway world orbiting another star may be home to life and “the first hints… of an alien world”.
Researchers believe the exoplanet K2-18b, which orbits a star 124 light-years from Earth, is a “Hycean planet” — meaning it’s home to an abundance of life-signifying molecules, including one that is only produced on Earth by living organisms such as marine algae, according to a new report.
K2-18b — which is eight times the size of Earth— shows signs of the unique molecule dimethyl sulphide, according to a new study published in the Astrophysical Journal on Wednesday.
“This is a revolutionary moment,” Dr Nikku Madhusudhan, an astronomer at the University of Cambridge and author of the study, said at a news conference Tuesday, according to NPR.
“These are the first hints we are seeing of an alien world that is possibly inhabited,” he claimed.
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The organic compound, composed of sulphur, carbon, and hydrogen, is naturally produced by phytoplankton and sometimes in bacteria in beer, and appears en masse over Earth’s oceans, the New York Post reported.
Madhusudhan and his team reported taking atmospheric measurements of the dimethyl sulphide on K2-18b back in 2023, and confirmed the molecule’s overwhelming presence in tests conducted last year with the James Webb Space Telescope.
Those signals from the life-byproduct were so strong that researchers had to work diligently to omit their presence while conducting other tests — dimethyl sulphide measured at 1,000 times the levels found on Earth, according to the study.
Despite his enthusiasm, Madhusudhan noted that the detection of these gases needs to be confirmed with more telescope observations.
“Hycean” is a term coined by Dr Madhusudhan in 2021 for a sub-species of exoplanets called “sub-Neptunes” with liquid oceans and hydrogen-rich atmospheres, which they believed at the time applied to K2-18b.
K2-18 b orbits in the “habitable zone” — a distance where liquid water, a key ingredient for life, can exist on a planetary surface — around a red dwarf star smaller and less luminous than our sun, located about 124 light-years from Earth in the constellation Leo.
A light-year is the distance light travels in a year, 9.5 trillion kilometres. One other planet has also been identified orbiting this star.
About 5 800 planets beyond our solar system, called exoplanets, have been discovered since the 1990s.
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