Paris | Jagran News Desk: Scientists from University College London on Wednesday said that they have discovered water in the atmosphere of an exoplanet with Earth-like temperatures that could support life.

The planet -- K2-18b -- is eight times the mass of Earth and twice as big. The planet is also in its star's "habitable zone" and water can exist there.

“This planet is the best candidate we have outside our solar system" in the search for signs of life, co-author Giovanna Tinetti, an astronomer at University College London,” they told AFP.

“We cannot assume that it has oceans on the surface but it is a real possibility,” they added.

They added that this is the first time when an exoplanet has been discovered with a rocky surface and an atmosphere with water.

Most exoplanets with atmospheres are giant balls of gas, and the handful of rocky planets for which data is available to seem to have no atmosphere at all.

“Finding water in a potentially habitable world other than Earth is incredibly exciting,” said lead-author Angelos Tsiaras from University College London.

“K2-18b is not 'Earth 2.0. However, it brings us closer to answering the fundamental question: is the Earth unique?” he added.

Tsiaras and his team work with spectroscopic data captured in 2016 and 2017 by the Hubble Space Telescope and use open-source algorithms to analyse the starlight filtered through K2-18b's atmosphere.

They found the unmistakable signature of water vapour. Exactly how much remains uncertain, but computer modelling suggested concentrations between 0.1 and 50 percent.

By comparison, the percentage of water vapour in Earth's atmosphere varies between 0.2 percent above the poles, and up to four percent in the tropics.

There was also evidence of hydrogen and helium as well. Nitrogen and methane may also be present but with current technology remain undetectable, the study said.

Further research will be able to determine the extent of cloud coverage and the percentage of water in the atmosphere.

Meanwhile, UCL astronomer Ingo Waldmann said that it is likely that this is the first of many discoveries of potentially habitable planets.

“This is not only because super-Earths like K2-18b are the most common planets in our galaxy, but also because red dwarfs -- stars smaller than our Sun -- are the most common stars,” he said.  

Posted By: Aalok Sensharma