Hycean worlds: New frontier in extraterrestrial life's quest

Public perceptions of alien life, shaped largely by science fiction, often revolve around images of humanoid beings or caricatures of animals roaming a planet similar to our own.

- Kabir Firaque

NEW DELHI: In the real world, scientists usually look for no more than microbial life; in fact, they look only for signs that indicate such life could exist away from Earth.

One aspect has been common to both worlds, though. As in science fiction, real-world scientists have long viewed rocky planets that are just the right distance from their respective stars (or "within the habitable zone") as being ideal candidates for supporting life. Given that life exists on Earth, is it not reasonable to suppose that any other inhabited planet will have conditions similar to our own?

Not anymore. Without ruling out the possibility that a rocky planet somewhere out there could be home to some form of life, a new school of scientific thought has been exploring another kind of world that could be potentially inhabitable—or even inhabited. Such as K2-18b, the subject of a promising new study published in The Astrophysics Journal Letters.

K2-18b is 2.6 times larger than Earth and an exoplanet, or a planet far from our Solar System: 124 light years away in this case, and orbiting its star in the habitable zone. It has now shown the strongest signs yet of a possible signature of life, scientists have announced—while also calling for caution in interpreting their findings, which they arrived at using data from NASA's James Webb Space Telescope. K2-18b is not a rocky planet but a potential "Hycean world", a new kind of inhabitable world first proposed by the same team of scientists.

Apart from the potential biosignatures themselves, the takeaways from the announcement include Webb's role in performing what it was primarily designed for, the cautionary reminder that the findings may not mean what scientists hope they mean, and the promise of a new area to explore. All these years, were scientists looking in the wrong place?