London: Scientists for the 1st time have detected water in the atmosphere of an Earth-like planet orbiting a distant star, evidence that a Key ingredient for life exists beyond our solar system, 110 light-years away.
The latest discovery was reported in research by a team of scientists at University College London (UCL) published in the peer-reviewed journal Nature Astronomy.
“This is the first detection of this kind,” says Angelos Tsiaras, an astronomer at University College London (UCL), UK, and lead author of a paper published in the journal Nature Astronomy. “This is the only planet we know outside the Solar System that has the correct temperature to support water, has an atmosphere, and has water in it,” he says, “making this planet the best candidate for habitability that we know right now.”
While light from the Sun takes several minutes to reach Earth, light from K2-18b’s star takes a century to reach our planet, “so for us to travel there is impossible,” he said.
“We’re talking about a planet twice the size of the Earth and eight times the mass,” Tsiaras says. Not only does that mean that the surface gravity is nearly twice that of Earth, but even though its star is cool, dim, and red, it probably receives significantly more ultraviolet radiation than we do on Earth.
K2-18b, which is eight times the mass of Earth, is now the only exoplanet known to have both water and temperatures that could be potentially habitable, according to the study published in the journal Nature Astronomy.
The planet orbits the cool dwarf star K2-18, which is about 110 light years from the Earth in the Leo constellation, noted the researchers who used data from ESA/NASA Hubble Space Telescope. The discovery is the first successful atmospheric detection for an exoplanet orbiting in its star’s ‘habitable zone’, at a distance where water can exist in liquid form, they said.
K2-18b is not ‘Earth 2.0’ as it is significantly heavier and has a different atmospheric composition. However, it brings us closer to answering the fundamental question: Is the Earth unique? said Tsiaras. The team used archive data from 2016 and 2017 captured by the Hubble Space Telescope and developed open-source algorithms to analyse the starlight filtered through K2-18b’s atmosphere.
The results revealed the molecular signature of water vapour, also indicating the presence of hydrogen and helium in the planet’s atmosphere, researchers said. They believe that other molecules including nitrogen and methane may be present but, with current observations, they remain undetectable. The researchers noted that given the high level of activity of its red dwarf star, K2-18b may be more hostile than Earth and is likely to be exposed to more radiation.
Further studies are required to estimate cloud coverage and the percentage of atmospheric water present, the researchers said. However, the discovery brings astronomers closer to answering the fundamental question of how unique Earth is in the Universe, the scientists said.