Life doesn't have to look the same everywhere.
When we look for life in faraway places, we generally look for planets that look like our own in terms of size, mass, temperature, and atmospheric composition. However, astronomers from the University of Cambridge have recently discovered a new class of exoplanets that are substantially different from our own but could potentially host life.
This revelation could accelerate the search for life outside our Solar System, bolstering the belief that biosignatures of life could be discovered within the next two or three years.
Hydrogen and ocean worlds
As reported in the study published in The Astrophysical Journal, this new class of habitable worlds, dubbed 'Hycean' planets which is a portmanteau of the words hydrogen and ocean, are hot and covered in massive planet-wide oceans with hydrogen-rich atmospheres. Hycean planets are somewhat similar to what would happen if Earth and Neptune had a baby, and they are more abundant in the universe and easier to notice than planets similar to Earth, which is why these neglected exoplanets could be promising candidates in the ongoing search for alien life.
The researchers, led by Nikku Madhusudhan from Cambridge’s Institute of Astronomy, have identified prime Hycean candidates, and while these are bigger and hotter than our planet, they still have the traits to host huge seas capable of supporting microbial life equivalent to those observed in Earth's most harsh aquatic settings.
The team also provided a set of biosignatures that astronomers should look for while searching for these worlds, as well as a list of promising Hycean candidates that are, in cosmic terms, nearby.
The researchers have discovered 11 possible Hycean worlds orbiting neighboring stars, all of which are red dwarfs between 35-150 light-years away and regarded as good biosignature targets. The most promising of these is K2-18b, and it will be observed with the James Webb Space Telescope, which is scheduled to be launched later this year.
"A biosignature detection would transform our understanding of life in the universe," says Dr. Nikku Madhusudhan. "We need to be open about where we expect to find life and what form that life could take, as nature continues to surprise us in often unimaginable ways."