Hot-Jupiter exoplanet illustration. (c) NASA

Using the Hubble telescope, astronomers have identified faint signals of water in the atmosphere of five exoplanets. The alien planets, however, are classed as hot-Jupiters – huge planets with a surface temperature too hot to support life. Finding water on planets light years away from Earth is definitely of great note and marks a step forward in scientists’ quest (and whole of mankind for that matter) of discovering life supporting planets outside our solar system and alien life itself.

With the help of Hubble’s Wide Field Camera 3, NASA researchers closely followed five planets: WASP-17b, HD209458b, WASP-12b, WASP-19b and XO-1b. All of these planets are extremely far away, as you can imagine, so naturally analyzed the light absorbed by the atmosphere of these planets to see what it’s made of. Light can tell you a great deal about the chemical composition of a planet as certain wavelengths are absorbed by certain molecules only – this method is called spectroscopy.

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All five planets showed signs of water in their atmosphere, with the strongest signatures found in WASP-17b and HD209458b, as reported in two separate studies published by NASA researchers in the Astrophysical Journal.

“We’re very confident that we see a water signature for multiple planets,” Avi Mandell, of NASA’s Goddard Space Flight Center in Greenbelt, Md., lead author of one of the studies, said in a statement. “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.”

This isn’t the first time signs of water have been found in the atmosphere of distant worlds, however the two studies mark the first time researchers measured and compared profiles of the substance in detail across multiple alien worlds. For all planets, the water signature was fainter than expected, based on previous observations with Spitzer, possibly due to hazes absorbing in the NIR or non-solar compositions.

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Faint or not, it’s highly likely that water is present in the air of these worlds. It’s little steps like these that might eventually help scientists refine their methods and lead to the milestone discovery we’re all waiting for.

“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,” Heather Knutson of the California Institute of Technology in Pasadena, a co-author on Deming’s paper, said in a statement. “This suggests that cloudy or hazy atmospheres may in fact be rather common for hot Jupiters.”