Washington: A team of scientists using NASA's Hubble Space Telescope has discovered an immense cloud of hydrogen escaping from a warm Neptune- sized exoplanet, thus boosting the the prospect of finding ocean-bearing exoplanets.

Such a phenomena not only helps explain the formation of hot and rocky 'super-earths', but also may potentially act as a signal for detecting extrasolar oceans, the study said.

"Escaping gas has been seen in the past for larger gas giant exoplanets, so it was a surprise that looking at a much smaller planet resulted in such a big and stunning comet-like display," said study co-author David Sing, professor at University of Exeter in Britain.

With a mass approximately 23 times that of our Earth located 33 light years away, the exoplanet GJ436b rotates around its star in only three days and has an atmosphere which leaves behind a gigantic trail of hydrogen.

The scientists were able to see this hydrogen cloud's shadow when it passes in front of the star.

"This cloud is very spectacular, though the evaporation rate does not threaten the planet right now."

GJ436b resides very close to its star — less than two million miles — and whips around it in just 2.6 Earth days. In comparison, the Earth is 93 million miles from our sun and orbits it every 365.24 days.

The team's results are presented in the journal Nature. (IANS)