Exoplanet K2-18 b (Illustration). NASA, CSA, ESA, J. Olmstead (STScI), N. Madhusudhan (Cambridge University)

Webb Finds Distant World Harbors Molecule Made Only by Life on Earth

Astronomers identified the presence of of dimethyl sulphide (DMS), a molecule on Earth only produced by living organisms, on the exoplanet Ks 18b, which curiously orbits its star in the so-called habitable zone.


Key takeaways:

  • The James Webb Space Telescope detects carbon-bearing molecules, methane and carbon dioxide, in K2-18 b’s atmosphere.
  • K2-18 b, 8.6 times the mass of Earth, revolves around the cool dwarf star K2-18.
  • Unique among celestial bodies, K2-18 b is a ‘sub-Neptune’—a category not present in our Solar System.
  • Research suggests K2-18 b might be a Hycean exoplanet, with both a hydrogen-rich atmosphere and an ocean-covered surface.
  • The Hycean classification makes K2-18 b a tantalizing candidate in the search for life.
  • Initial data hints at the presence of dimethyl sulphide (DMS), a molecule on Earth only produced by living organisms.
  • Webb’s unmatched sensitivity brought these findings to light with just two observations.
  • Future observations using Webb’s #MIRI will aim to validate these discoveries and provide more detailed insights.

As the realms of astronomy and astrobiology converge, fresh data from the NASA/ESA/CSA James Webb Space Telescope unveils transformative insights about K2-18 b, an exoplanet that may reshape our understanding of life’s possibilities beyond Earth.

Unveiling the Secrets of K2-18 b

Located a substantial 120 light-years away within the Leo constellation, K2-18 b has often piqued astronomers’ interests, especially as it orbits within its star’s habitable zone. This exoplanet, with a mass much larger than Earth’s but smaller than Neptune’s, stands out due to its uniqueness — it’s unlike any planet in our Solar System.

The new revelations concerning K2-18 b’s atmosphere are particularly stirring, marking it as potentially one of the most intriguing places to search for life beyond our home planet. Furthermore, the potential classification of this planet as a Hycean world means it may possess vast oceans beneath a dense atmosphere, conditions that might just be right for life.


From Speculation to Revelation

The primary observations, initially using the Hubble Space Telescope, only scratched the surface of K2-18 b’s mysteries. With the more sophisticated James Webb Space Telescope, however, a clearer picture emerges. And it’s this superior technology that led to the discovery of carbon-bearing molecules in the exoplanet’s atmosphere.

Perhaps most tantalizingly, the telescope’s data hints at the molecule dimethyl sulphide (DMS). On Earth, DMS is only produced by living organisms, especially marine phytoplankton. If confirmed, this could have profound implications for the potential of life on such planets.

Challenges & Anticipation

Studying distant exoplanets is no simple task. The bright glare from their parent stars often overshadows these celestial bodies, making detailed observations challenging. Yet, the Webb Telescope’s unmatched sensitivity allowed for the extraction of these pivotal details from just two transits. With future observations using Webb’s advanced instruments, our understanding of K2-18 b will only deepen.


The discoveries about K2-18 b are just the beginning. They represent a significant leap towards understanding the myriad worlds that populate our galaxy and the potential they hold for life.

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Written by Ivan Petricevic

I've been writing passionately about ancient civilizations, history, alien life, and various other subjects for more than eight years. You may have seen me appear on Discovery Channel's What On Earth series, History Channel's Ancient Aliens, and Gaia's Ancient Civilizations among others.

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