Water has been discovered for first time in atmosphere of an exoplanet with Earth-like temperatures that could support life as we kw it, scientists revealed Wednesday. NASA's Hubble telescope is responsible for this discovery. Eight times mass of Earth and twice as big, K2-18b orbits in its star's "habitable zone" at a distance. This distance is neir too far r too close -- where water can exist in liquid form, y reported in journal Nature Astromy.

Water discovered on exoplanet

READ |US Geologists suspect many 'precious metals' hidden below Moon surface 

"This planet is best candidate we have outside our solar system" in search for signs of life, co-author Giovanna Tinetti, an astromer at University College London, told AFP. "We cant assume that it has oceans on surface but it is a real possibility."  Of more than 4,000 exoplanets detected to date, this is first kwn to combine a rocky surface and an atmosphere with water.

READ |Aryan Invasion ory busted, 5000-year old Harappan geme sequenced

What is K2-18b?

Most exoplanets with atmospheres are giant balls of gas, and handful of rocky planets for which data is available seem to have atmosphere at all. Even if y did, most Earth-like planets are too far from ir stars to have liquid water or so close that any H2O has evaporated. Discovered in 2015, K2-18b is one of hundreds of so-called "super-Earths" -- planets with less than ten times mass of ours -- spotted by NASA's Kepler craft. Future missions are expected to detect hundreds more in coming decades.

"Finding water in a potentially habitable world or than Earth is incredibly exciting," said lead-author Angelos Tsiaras, also from UCL. "K2-18b is t 'Earth 2.0'," he said. "However, it brings us closer to answering fundamental question: is Earth unique?" 

READ | NASA's James Webb telescope assembled, ready to succeed iconic Hubble

How did y find water on K2-18b?

Working with spectroscopic data captured in 2016 and 2017 by Hubble Telescope, Tsiaras and his team used open-source algorithms to analyse starlight filtered through K2-18b's atmosphere. y found unmistakable signature of water vapour. Exactly how much remains uncertain, but computer modelling suggested concentrations between 0.1 and 50 per cent. By comparison, percent of water vapour in Earth's atmosphere varies between 0.2 percent above poles and up to four per cent in tropics. re was also evidence of hydrogen and helium as well. Nitrogen and methane may also be present but with current techlogy remain undetectable, study said.

WATCH | line: Scientists suggest cable connecting Moon and Earth

What lies ahead?

Furr research will be able to determine extent of cloud cover and percent of water in atmosphere. Water is crucial in search for life, in part because it carries oxygen. "Life, as we kw, is based on water," said Tinetti. "It is likely that this is first of many discoveries of potentially habitable planets," said UCL astromer Ingo Waldmann, also a co-author, adding, "This is t only because super-Earths like K2-18b are most common planets in our galaxy, but also because red dwarfs -- stars smaller than our Sun -- are most common stars." 

K2-18b orbits a red dwarf star about 110 light-years distant -- a million billion kilometres -- in Leo constellation of Milky Way. It is probably bombarded by more destructive radiation than Earth. new generation of -based star gazing instruments led by James Webb Telescope and European ncy's ARIEL mission will be able to describe exoplanet atmospheres in far greater detail. ARIEL, slated for a 2028 launch, will canvas some 1,000 planets, a large eugh sampling to look for patterns and identify outliers.