NASA finds water in atmosphere of five distant planets

In an encouraging sign of life beyond earth, NASA scientists have found faint signatures of water in the atmospheres of five distant planets.

Though the presence of atmospheric water was reported previously on a few exoplanets orbiting stars beyond the solar system, but this is the first study to conclusively measure and compare the profiles and intensities of these signatures on multiple worlds, NASA said.

The five planets - WASP-17b, HD209458b, WASP-12b, WASP-19b and XO-1b - orbit nearby stars, a NASA report said adding that this was based on the research done through the Hubble telescope.

The strengths of their water signatures varied, it said. WASP-17b, a planet with an especially puffed-up atmosphere, and HD209458b had the strongest signals.

The signatures for the other three planets, WASP-12b, WASP-19b and XO-1b, also are consistent with water, NASA said. "We're very confident that we see a water signature for multiple planets," said Avi Mandell, a planetary scientist at NASA's Goddard Space Flight Center in Greenbelt, Maryland., and lead author of an Astrophysical Journal paper, published on Tuesday, describing the findings for WASP-12b, WASP-17b and WASP-19b.

"This work really opens the door for comparing how much water is present in atmospheres on different kinds of exoplanets, for example hotter versus cooler ones," Mandell said.

NASA said the five planets are hot Jupiters, massive worlds that orbit close to their host stars. The researchers were initially surprised that all five appeared to be hazy.

"These studies, combined with other Hubble observations, are showing us that there are a surprisingly large number of systems for which the signal of water is either attenuated or completely absent," said Heather Knutson of the California Institute of Technology, a co-author.

"This suggests that cloudy or hazy atmospheres may in fact be rather common for hot Jupiters," he added.