It's not Earth 2.0 but it's the first time water has been found on another planet
- Scientists have found a planet 110 million light years from Earth that could have water on its surface.
- The planet, K2-18B, is eight times the size of Earth and, hence, has more gravity.
- Ultimately K2-18B might be hostile to life since it has been exposed to high-energy radiation.
Using data from the National Aeronautics and Space Administration's (NASA) Hubble Space Telescope, scientists have for the first time discovered water vapour signatures in the atmosphere of a distant planet called K2-18b.
It is located in the habitable zone of its star around 110 light years away from Earth, where conditions can lead to the formation of liquid water and the proliferation of life.
"Finding water in a potentially habitable world other than Earth is incredibly exciting," said Angelos Tsiaras, author of the study published in Nature Astronomy.
If confirmed by further studies, this will be the only planet known to have both water in its atmosphere and temperatures that could sustain liquid water on a rocky surface.
Even though it has water, K2-18b may be hostile to life since it is likely to be exposed to more high-energy radiation.
"K2-18b is not 'Earth 2.0' as it is significantly heavier and has a different atmospheric composition," said Tsiaras.
It's mass also eight times that of earth, which means it also has a lot more gravity.
"This study contributes to our understanding of habitable worlds beyond our Solar System and marks a new era in exoplanet research, crucial to ultimately place the Earth, our only home, into the greater picture of the Cosmos," said Tsiaras.
In search of water
The team used archive data from 2016 and 2017 captured by Hubble and developed open-source algorithms to analyse the host star's light filtered through K2-18b's atmosphere.
Liquid water would only be possible if the planet turns out to be terrestrial in nature, rather than resembling a small version of Neptune.
The results revealed the molecular signature of water vapour, and also suggest the presence of hydrogen and helium in the planet's atmosphere. Other molecules, including nitrogen and methane, may be present but they remain undetectable with current observations.