A discovery in the astronomical field has the scientific community on edge: an international team of researchers has identified Unusual chemical signals in the atmosphere of exoplanet K2-18b, located about 124 light-years away, which could be related to biological processes. This discovery, although still far from being a definitive confirmation, represents the most significant advance to date in the search for extraterrestrial life.
The exoplanet K2-18b, located in the constellation Leo, is part of a class of planets known as Hyceans, characterized by their intermediate size between Earth and Neptune, and by their potential to host liquid oceans under dense hydrogen-rich atmospheresThese types of worlds are considered promising in astrobiological terms, especially for their ability to maintain stable conditions over time.
An atmosphere with possible biological traces
Using the sophisticated instruments of the James Webb Space Telescope, the team of astronomers managed to detect in the atmosphere of K2-18b spectral signals corresponding to dimethyl sulfide (DMS) and dimethyl disulfide (DMDS). These compounds, on Earth, have an exclusively biological origin, mainly attributable to marine microorganisms such as phytoplankton.
The identification of these elements was carried out through the technique of spectroscopy during the transits of the planet in front of its starThis methodology allows us to analyze how certain wavelengths of starlight are absorbed by the planet's atmospheric gases, revealing its composition.
The first hints of these molecules were captured by the JWST's NIRISS and NIRSpec instruments, operating in the near-infrared range. Subsequently, a complementary observation with the MIRI module, specialized in the mid-infrared, confirmed the presence of the same signals with greater clarityThis instrumental redundancy provides greater robustness to the acquired data.
According to scientists, the presence of DMS and DMDS in amounts thousands of times greater than those observed on our planet could imply the existence of some type of biological activity. However, they acknowledge that It is also possible that these substances are generated by non-biological chemical processes still unknown in this type of planetary environments.
A possible Hycean world
K2-18b has a mass approximately eight times higher to that of the Earth and a diameter about 2,6 times larger. The location in the habitable zone of its host star indicates that it may exist water in liquid state, fundamental to life as we know it.
Previous Webb telescope observations had already identified organic molecules such as methane and carbon dioxide in the planet's atmosphere, reinforcing the hypothesis that it is an environment conducive to habitability. These data are consistent with the existence of a Hycean planet, a world covered in oceans with a hydrogen-rich atmosphere.
This type of exoplanet is relatively new and, although they could not host complex intelligent life, yes they could support microbial organisms similar to the first living beings on EarthThe detection of potentially biological compounds under these conditions is particularly intriguing.
Interpretations, caution and next steps
The statistical confidence level of the finding is set at 3 sigma, which implies that there is a probability of 0,3% that the results are a coincidence. However, in science it is necessary to achieve the 5 sigma to consider a discovery confirmed, which is equivalent to a probability of error less than 0,00006%.
To obtain this certainty, the researchers plan to carry out between 16 and 24 additional hours of observation with JWSTThese sessions, scheduled for the coming months, will help more precisely verify the presence of these molecules.
Nikku Madhusudhan, astrophysicist at the University of Cambridge and lead author of the study, highlights that "It is essential to subject our conclusions to rigorous and skeptical analysis; only then can we firmly affirm the possible existence of life beyond Earth.".
Some outside experts have also expressed caution. In the past, other clues on K2-18b and other exoplanets have turned out to be false positives, such as the case of the water vapor initially detected, which was later identified as a different compound.
Are we close to a definitive answer?
This discovery revives one of humanity's oldest questions: are we alone in the universe? Although the evidence on K2-18b is still preliminary, it suggests that life, at least in simple forms, might not be exclusive to Earth.
This study represents an important advance in the technical capacity of current instrumentsThe possibility of identifying biosignatures through spectral observations from such long distances demonstrates the enormous potential of James Webb Telescope and future space telescopes under development.
As new data is collected and analyzed, K2-18b will continue to be a focus of interest in the coming years, raising the possibility that we are on the cusp of a decisive shift in our understanding of our place in the cosmos.
