A new discovery has overturned ideas about the search for extraterrestrial life

The first life discovered beyond the Solar System may turn out to be far from typical for the Universe. This is the conclusion reached by scientists from NASA Goddard Space Flight Center, who analyzed how astronomers usually make the first discoveries of new cosmic objects.

This was reported by the Universe Today (UT) portal.

The authors of the study note that the history of astronomy has repeatedly demonstrated the same pattern: the first objects to be discovered are not the most common ones, but the most conspicuous. For instance, the first confirmed exoplanet was found not around an ordinary star, but near a pulsar — an extremely exotic and rare object. The first discovered quasar turned out to be the brightest one visible from Earth, and the first detected "hot Jupiters" long created the false impression that such planets are found everywhere.

According to the researchers, the search for extraterrestrial life will face the same problem. Modern telescopes are capable of detecting only the strongest signals, so the first possible biosignatures — chemical signs of life in the atmospheres of exoplanets — will most likely be discovered not on the most typical habitable worlds, but on those where they are easiest to detect.

The James Webb Space Telescope plays a particularly important role here. It studies the atmospheres of exoplanets by analyzing starlight passing through a planet's gaseous envelope during its transit across the stellar disk.

The most detectable targets for such observations turn out to be sub-Neptunes — planets larger than Earth with thick hydrogen atmospheres. Thanks to their large sizes and atmospheric properties, they produce much stronger spectral signals than Earth-like planets.

As an example, the scientists cite the exoplanet K2-18b, located approximately 124 light-years from Earth. It is roughly 2.6 times the size of our planet and is considered one of the most promising targets for searching for possible biosignatures. According to the authors' calculations, a potential signal of signs of life from such a planet could be approximately 32 times stronger than from a full analog of Earth.

The researchers emphasize that the question of K2-18b's habitability remains a subject of scientific debate. However, the planet itself well illustrates the main problem: the most conspicuous objects are far from always the most typical ones.

According to the authors of the study, the detection of the first biosignature will become one of the greatest scientific discoveries in human history. However, the scientists warn: if the first signs of extraterrestrial life turn out to be unusual and nothing like those on Earth, this should not be surprising. And conversely, even if they resemble conditions on Earth, this does not necessarily mean that such life is the most common in the Universe.