In a groundbreaking discovery, NASA’s James Webb Space Telescope may have found clues to extraterrestrial life on a distant exoplanet known as K2-18b, which has 8.6 times the mass of Earth.
An upcoming study, scheduled for publication in The Astrophysical Journal Letters, describes how the James Webb telescope discovered a molecule called dimethyl sulfide (DMS), a substance generated exclusively by living organisms on Earth. In addition to DMS, the researchers also observed the presence of carbon-containing molecules, such as methane and carbon dioxide, in the exoplanet’s atmosphere.
The researchers were deeply puzzled by these initial findings, suggesting that K2-18b could have the potential to provide the first-ever confirmation of extraterrestrial life.
Astronomers have long paid attention to this distant world: it is located in the zone of potential habitability and is covered by an ocean.
This is how artists depicted this planet (see below) based on the available knowledge about it. It belongs to a small, faint star in the constellation Leo, the red dwarf K2-18. It is 120 light years away from us. That means that the light that comes out takes 120 years to reach us.
Unfortunately, K2-18 cannot be seen with the naked eye; it was only discovered in the early 2000s. And only in 2015 did it become clear that it has planets. This illustration shows the planet K2-18 b. It is 2.6 times larger than Earth and 8.6 times heavier in mass.
Moreover, the average density is only 2.4 grams per cubic centimeter. For comparison, the Earth has 5.5. Therefore, this planet is considered less of a super-Earth and more of a mini-Neptune.
According to scientists, it has a solid rocky core, but is covered by a thick mantle of real water. Partly in the form of ice, and partly in the liquid state.
In 2019, with the help of the Hubble telescope, it was possible to determine that the atmosphere of this planet contains 20 to 50 percent water vapor. In the Earth’s atmosphere, by the way, from 0.2 to 2.5 percent. This means that K2-18 b is an even more humid and watery world than ours. It is considered an ocean planet.
Moreover, it is only 21 million kilometers from the faint sun. This is almost three times closer to our star than Mercury. But because the sun is much weaker there, its little Neptune receives exactly the same amount of energy from its star as Earth receives from its own star.
K2-18 b is therefore in the so-called potentially habitable zone, that is, at the optimal distance from the star – at a distance that allows the maintenance of liquid water, and therefore life, that we cannot yet imagine ourselves without water can imagine.
The proximity of this exoplanet to the star leads us to believe that it orbits it, constantly “looking” at it with one side (like the moon around the Earth). This is called tidal fishing. And then it may well be that the ocean splashes right on the territory of eternal day, and on the side of endless night there is the same endless permafrost.
And now the most interesting thing: this planet was recently observed by the famous “replacement” of Hubble – the Webb Space Telescope, which, as we remember, is located one and a half million kilometers from Earth.
Webb ‘viewed’ and captured K2-18 b during its transit across the star’s disk. The fact is that at this time the light from the star passes through the atmosphere of the planet and is reflected in it in different shades, depending on what substances are in the atmosphere.
And Webb is able to capture these hues and thus determine the composition of the atmosphere from the spectrum. And the resulting spectrum shows that there is carbon dioxide, methane and something even stranger.
In principle, even methane is a reason to suspect that there may be life activity on the planet, because it is actively emitted here on Earth by our microscopic inhabitants.
However, there are also non-biological sources, so the presence of methane is not yet a strong enough argument in favor of extraterrestrial life. But a rather smelly, colorless liquid called dimethyl sulfide is indeed a very serious argument for the habitability of K2-18 b.
On Earth at least, this substance is not produced in any way except as a result of life activity. It is mainly a product of marine phytoplankton, that is, microalgae, and is also released by bacteria into sewers and wastewater. And according to Webb’s spectral analysis, there is one on a distant planet in the constellation Leo.
“We are slowly moving towards the point where we can answer the big question of whether we are alone in the universe or not,” says deputy director of the Royal Astronomical Society of London, Dr Robert Massey. told the BBC.
“I am optimistic that one day we will find signs of life. Maybe it will be this. Perhaps in ten or even fifty years we will have evidence so compelling that it is the best explanation.”
The research team will further investigate K2-18b using James Webb’s MIRI spectrograph (Mid-Infrared Instrument). Their goal is to strengthen the credibility of their initial findings and to delve deeper into the environmental characteristics of this remote planet. They are optimistic about confirmation of these early chemical clues to life in the coming year.
