A Last paper approved by Astrophysics Journal It garnered a lot of attention, and for good reason. Niko Madhusudan and colleagues from the University of Cambridge have taken a closer look at a new type of habitable exoplanet, which they call the Hycean world. These planets lie between “super Earths” and “mini Neptunes” in terms of mass. They are believed to have sufficient gravity to maintain a thick hydrogen atmosphere over a sea of liquid water.
Such a planet, floating alone in interstellar space – in other words, not orbiting a star –Previously recognized It can be livable. Madhusudhan carried out more detailed investigations, including modeling different scenarios, and concluded that habitable temperatures and pressures would be very common on this type of planet. Indeed, they say, many of them can accommodate life. The authors suggest that certain particles suggesting life could be detected by the soon-to-be-launched James Webb Telescope, although they would only be present in very low concentrations in a hydrogen-dominated atmosphere.
The authors believe that a Hycean planet with a mass 10 times that of Earth is habitable even if gradually closed (Dark Hycean Realm) or have no parent star (Cold Hycean Realm). The latter will, in principle, be like the others “bad” planet.
Given the number and variety of exoplanets already classified, I agree that there must be more planets lying in the mass range between super-Earth and minor Neptune. But I think a fraction of that can be expected to be truly livable, and even less so that it can accommodate life.
We don’t have a Hycean world in our solar system, which doesn’t mean it can’t be common elsewhere, of course. We have Neptune, that is It is believed to have an ocean of liquid water in its atmosphere. However, this is not where we seek life. Habitability requires more than harmless temperature and pressure to keep water liquid. It also requires sources of energy, the right organic building blocks, and mechanisms to recycle nutrients, such as plate tectonics. Even if a planet has all of these, it doesn’t mean that it harbors life, as there are likely to be many planets that are habitable, but uninhabited.
The reason is that the barriers to life that appear initially are much more stringent than the barriers to continuing life, because once formed they can adapt by natural selection to various environments, even extreme ones. And even if life originated in the Hycean realm, expect nothing more from microbes. Due to the lack of oxygen or other compounds to provide much of the metabolic energy, animal life is not a realistic option.
So while I agree with the authors that we should look for molecules that lead to life (called biosignatures), such as methyl chloride, dimethyl sulfide, and carbonyl sulfide, we should not get our hopes up. Keep in mind that Venus’ atmosphere contains a lot of carbonyl sulfide, but it may not have a lifetime at this time, and the discovery of these molecules would be uncertain.
As such, I think the authors deserve credit for suggesting the possibility of life in a world very different from ours. One common mistake is that we often focus on Earth in our search for life in the universe.
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