Water on the surfaces of exoplanets – remote planets outside our solar system – much less than they thought. Therefore, exoplanets do not have thick layers of water, as previously expected scientists.
This is evidenced by the results of a new study of the international group of scientists, the press service of the Federal Higher Technical School of Zurich (Eth Zurich, Switzerland) reports.
It is noted that there are many planets in space, more than Earth, but less Neptune. There are no planets in our solar system, but observations show that they are widespread in outer space.
The study showed that the widespread assumption that such “subneptins” are aquatic worlds that can support life is unrealistic.
Scientists say that the water on the planets is much more limited than it thought.
Thus, in April 2025, media headings around the world were exoplanets K2-18B, which rotates around the dwarf star at a distance of 124 light years from the ground. At that time, researchers from the University of Cambridge reported that the K2–18B planet could be the sea world with a deep global ocean that boils life.
Nevertheless, studies now show that the so-called subneptins, such as K2-18B, are hardly worldly in which water dominates, and that the conditions are far from favorable for life, the Eth Zurich Press service incites.
By this time, it was believed that some of these planets can accumulate, especially a large amount of water during their formation and now contain deep global oceans under a rich hydrogen atmosphere. Experts call them Hycean planets: a combination of words “hydrogen” and “ocean”.
Our calculations show that this scenario is impossible, ”the scientists say.
It is noted that the fundamental drawback of previous studies was that they ignored some kind of chemical connection between the atmosphere and the internal parts of the planet. In this study, scientists took into account such an interaction.
Researchers suggest that at the early stage of their formation, Subneptuna passed through the phase, in which they were covered with a deep hot ocean of Magma. The gas shell of hydrogen has provided this phase for millions of years.
For this, researchers used an existing model that describes the evolution of the planets for a certain period of time. They combined it with a new model that calculates the chemical processes that occur between gas in the atmosphere and metals and silicates in magma.
Researchers calculated the state of chemical balance of 26 different components of a total of 248 planets. Computer modeling showed that:
- Chemical processes destroy the majority of H2O water molecules;
- Hydrogen (h) and oxygen (O) are attached to metal compounds, and they mainly disappear in the nucleus of the planet.
Despite the fact that the accuracy of such calculations has some restrictions, researchers are convinced of the results.
We focus on the main trends and we can be clearly visible in modeling that there are much less water on the planets than they initially accumulated, ”the scientists say. – Water, which actually remains on the surface, since H2O is limited at least a few percent.
According to calculations, there are no distant worlds with massive layers of water, where water is about 50 percent of the weight of the planet, as it was thought. Thus, the worlds of Hycean with 10-90 percent of water are very unlikely, – the researchers add.
Thus, this complicates the search for extraterrestrial life – the conditions that are favorable for life, with sufficient liquid water on the surface, probably exist only on small planets, which will probably be fixed only when the spatial observatories are better than the existing space telescope James Webb.
At the same time, this makes the role of our land especially interesting – calculations show that the most remote planets have a similar content of water on our planet.
Earth may not be as extraordinary as we think. At least in our study, this is, according to, a typical planet, ”the scientists say.
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Source: Racurs
I am David Wyatt, a professional writer and journalist for Buna Times. I specialize in the world section of news coverage, where I bring to light stories and issues that affect us globally. As a graduate of Journalism, I have always had the passion to spread knowledge through writing.