For the first time, scientists have found traces of water in the atmosphere of an Earth-like planet orbiting a distant star, providing evidence that a key element for life exists beyond the solar system, according to a study published on Wednesday.
Water vapour was found in the atmosphere of K2-18b — one of the hundreds of "super-Earths" that range in size between the Earth and the planet Neptune, according to a new field of astronomy that studies the so-called exoplanets that exist elsewhere in the Milky Way galaxy.
More than 4,000 exoplanets of all types and sizes have been detected overall.
The research was carried out by a team of scientists at the University College London (UCL) and was published in the journal Nature Astronomy.
"We found water," UCL astrophysicist Ingo Waldmann told Reuters. The liquid was found using the Hubble Space Telescope, which analysed starlight filtered through K2-18b's atmosphere.
This is the first time that scientists have found water in the atmosphere around a super-Earth.
Angelos Tsiaras, an astronomer at UCL, said the team of researchers were concentrating on finding exoplanets with conditions similar to those of the Earth.
"But of course this is not in order to find a place where we could go. This is still science fiction," Tsiaras said, noting that K2-18b orbits a dwarf star in the constellation Leo that lies 100 light-years from Earth.
Because light from the K2-18b's star takes a century to reach the Earth, to travel over there would be "impossible," he said.
"Given it's so far away we don't really have any other choice but stay on our own Earth, so it's important to make Earth great again rather than looking for an alternative to go to," Tsiaras said.
Additionally, the fact that the exoplanet is exposed to far more radiation than Earth, the prospects of life evolving there are quite small.
However, the discovery brings astronomers closer to answering the fundamental question of how unique Earth is in the universe, the scientists said.