The search for extraterrestrial life forms has a new epicenter. It is called K2-18B, and is an exoplanet located 124 light years from the earth, in the constellation of the lion. For years, in fact, the researchers who have observed it with the help of the James Webb space telescope: first revealing the presence of methane and carbon dioxide in its atmosphere, compatible with the possibility that it belongs to a class of potentially habitable planets so far as hypothetical, known as Planets Iceani; And now, showing the presence of two chemicals that are produced only by biological sources on earth (mainly by algae). The new discovery is detailed in a research just published in The Astrophysical Journal Letters by a team of Cambridge, and represents the most convincing clue ever found to date of the possible presence of alien life forms outside the Earth’s atmosphere.
I take you to the exoplanet K2-18b
As we mentioned, K2-18B would seem to belong to the category of Iceani planets, celestial bodies whose existence was hypothesized only a few years ago, and towards which many of the research of traces of extraterrestrial life forms are being oriented. Planets of relatively small size, like our land, are in fact not easy to identify and study with current technologies. For this reason, the observations must necessarily focus on medium -sized planets, intermediate between the terrestrial ones and those of Neptune. Classically there are two types: super lands, rocky, and mininettuno, gaseous.
The gaseous planets that we know of the first hand, in our sun system, are all located outside the area of the sun, where it is too cold because liquid water is present. What do I wait for a mininettuno located closer to your star? This is what three astronomers of Cambridge, Nikku Madhusudhan, Anjali Piette and Savvas Constantinou, were asked, coming to a conclusion proposed in 2021: they would be Iceani planets, in fact, covered with a deep ocean of liquid water, surrounded by a rich hydrogen atmosphere. Planets that would have all the characteristics to host life, and which can be studied with relative ease with telescopes such as James Webb.
About a dozen have already been identified, and among these K2-18B for now it is the most studied, and also the most promising. In 2023 it was confirmed that he has an atmosphere compatible with that of an ocean planet. And now, the new study of Cambridge researchers presents very convincing evidence of the presence in its atmosphere of the biophilame associated with life, at least on our planet.
The traces of life
The detailed analyzes in the new research reveal the probable presence of dimetylsolfuro (DMS) and dimetildisulfuro (DMDS), two chemical compounds that are introduced into the terrestrial atmosphere mainly by the activity of the phytoplankton, and of which a non -biological source is not known. In the study, the researchers admit that the level of certainty is currently “three sigma”, that is, the statistical significance of their observations makes them certain to 99.7 percent. Therefore, but not to the point of considering them as a real discovery: for that the statistical significance must reach “five sigma”, that is, to a probability of 99,99999 percent that prove accurate.
Even when the presence of the two substances in the atmosphere of K2-18B will be confirmed, it will remain the mystery of their origin. As we said, on earth they are produced by algae. And since it is a world covered by an immense ocean, it could be assumed that it is the same on this exoplanet. However, nothing prevents things that things are otherwise. And that instead of having discovered life, we find ourselves discovered that the two substances in question can also be produced by non -biological sources. In short, the way to have some certainty is still long.