In a first, scientists find water on earth-like planet that can support life 110 lightyears away

Washington, Sep 12: In a first, scientists have discovered water vapor and possibly even liquid water clouds that rain in the atmosphere of an Earth-size planet.

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.

K2-18 b lies in its parent star's "habitable zone," the range of distances that could support the existence of liquid water on a world's surface. Two teams of scientists announced this week that they've found water vapor in this world's air a big milestone in the search for alien life.

The study, which has not yet been peer-reviewed, was published Tuesday (Sept. 10) in the preprint journal arXiv.org.

Incredibly exciting

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.

"Finding water in a potentially habitable world other than Earth is incredibly exciting," said first author Angelos Tsiaras from the University College London (UCL) in the UK.

K2-18b, super-Earth planet

K2-18b is one of hundreds of "super-Earths" - exoplanets with masses between those of Earth and Neptune - found by Kepler. NASA's TESS mission is expected to detect hundreds more super-Earths in the coming years. The next generation of space telescopes, including the James Webb Space Telescope, will be able to characterize exoplanet atmospheres in more detail.

K2-18b, is more hostile than Earth

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.

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. "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 co-author Ingo Waldmann from UCL

Is the Earth unique?

"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 ESA/NASA Hubble Space Telescope and developed open-source algorithms to analyse the starlight filtered through K2-18b's atmosphere.

Photo credit: Illustrious Images by NASA