As Space.com noted, "Because this study has found evidence for liquid water and hydrogen in this exoplanet's atmosphere and it lies within the habitable zone, there is a possibility that this world is habitable".
However, its red dwarf star is quite active which means it could be exposing the planet to lots of radiation, which would make K2-18b a much more hostile place than Earth. K2-18b is now the only super-Earth exoplanet known to host both water and temperatures that could support life.
As per the research, an exoplanet (planets present outside the solar system) called K2-18b has traces of water. It was discovered in 2015 by the Kepler Space Telescope orbiting closer to its sun within the "Goldilocks Zone".
Using the Hubble Space Telescope, a team from University College London performed a spectrographic survey of K2-18b's atmosphere, resulting in the detection of a distinctive water signature.
As Tsiaras said during a press conference, researchers consider K2-18b "the best candidate for habitability" outside our solar system.
"With so many new super-Earths expected to be found over the next couple of decades, it is likely that this is the first discovery of many potentially habitable planets".
Li Zeng, a planetary scientist at Harvard University not involved with the new study, said the results came as "no surprise", as he expects many exoplanets similar in size to K2-18b to have water "as a major constituent of their bulk interiors", he told Gizmodo in an email.
"This represents the biggest step yet taken toward our ultimate goal of finding life on other planets, of proving that we are not alone", said the study's lead astronomer, Bjorn Benneke of the University of Montreal.
Both teams found that water vapor is nearly certainly present in the atmosphere of this super-Earth. The report was published in the journal Nature Astronomy on Wednesday. Also, it is 110 light-years away from us and rotates around a red dwarf star, which is half the size of the sun. However, it brings us closer to answering the fundamental question: "Is the Earth unique?" study first author Dr Angelos Tsiaras said in a statement issued by UCL.
For the first time ever, astronomers have detected water vapour in the atmosphere of a rocky exoplanet. The researchers said they clearly saw the signature for water vapor in the atmosphere when they put the data through algorithms.
Ultimately K2-18B might be hostile to life since it has been exposed to high-energy radiation.
But the more important aspect of all this is that these observations show that finding water vapor in the atmospheres of temperate planets is possible. Models of planet formation indicate that K2-18b is probably large enough to have hung on to the hydrogen and helium that it started with, but the presence of other gasses in its atmosphere have yet to be determined. Further observations are needed to determine whether the planet is indeed a true water world, using next-generation observatories like NASA's James Webb Space Telescope and the European Space Agency's Ariel, both due to launch in the 2020s.
Benneke stated that although water exists in liquid water clouds on K2-18 b, the rain falls through thick gas before it hits the surface, heating it so it becomes gas before it reaches the planet's surface.