Liquid water would only be possible if the planet turns out to be terrestrial in nature, rather than resembling a small version of Neptune. This so-called Super Earth is just the right distance from its star to conceivably harbor life.
They also observed the signatures of hydrogen and helium in the atmosphere, two of the most abundant elements in the universe. In a paper just submitted to the Astronomical Journal for publication, these scientists suggest it might even be raining there.
"It is significantly heavier, and it has a different atmospheric composition", he said. Also, it is 110 light-years away from us and rotates around a red dwarf star, which is half the size of the sun.
"More than 4,000 exoplanets have been discovered but we do not know a lot about their makeup and temperament", explained Tinetti.
"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", said Ingo Waldmann, study co-author and lecturer in extrasolar planets at the University College London's Centre for Space Exochemistry Data.
If confirmed by further studies, this will be the only exoplanet known to have both water in its atmosphere and temperatures that could sustain liquid water on a rocky surface.
Now, as observed by NASA's Hubble Space Telescope, a habitable-zone exoplanet, dubbed as K2-18b, presents water vapor in its atmosphere.
K2-18b was discovered in 2015 and is one of hundreds of super-Earths - planets with a mass between Earth and Neptune - found by NASA's Kepler spacecraft.
Tsiaras: The next step will be to use the James Webb Space Telescope, it will be able to give us a much better spectrum of the planet.
For now, scientists know K2-18b takes 33 days to orbit its star, so one year there is one month here. Kelper used NASA's trick on how to keep the optics stable by using the solar panels to determine the existence of water on this potentially habitable planet. Pictured: A hand out image made available by the European Southern Observatory on August 24 2016, shows an artist's impression of the planet Proxima b orbiting the red dwarf star Proxima Centauri, the closest star to the Solar System.
Recently, an global team of researchers had discovered, with the participation of the University of Göttingen, three new planets, one of which may be habitable.
The surface, meanwhile, could be wet or dry. Either way, given the planet's mass, it would be hard to walk on the surface.
In contrast, the proportion of water vapor in the planet's atmosphere varies between 0.2 percent over the rods and around four percent at the tropics.