The search for life beyond our planet, as well as ways for life from our planet to travel to new ones, is one of the most compelling questions of our time, and central to this issue is liquid water. Scientists have discovered water vapor on a Neptune sized planet dubbed HAT-P-11b, 124 light years away from earth, the first non gas giant exoplanet with water found.

According to the BBC ,Dr Eliza Kempton from Grinnell College, Iowa, said, "Astronomers have detected water vapor in the atmospheres of larger planets - planets that are closer in size to Jupiter. But you can imagine that eventually we want to be able to detect molecules in the atmospheres of even smaller planets. We'd like to be able to look at an Earth-sized planet and measure its gaseous composition. So this is a step on the ladder; we're stepping down the ladder towards smaller and smaller planets."

HATT-P-11b, however, is a highly unlikely candidate to support life, the planet is about five times as big as Earth and likely has a deep gaseous atmosphere like Neptune. It orbits close its parent star at a distance of less than five million miles (eight million kilometers), compared with Earth's 93-million-mile distance, making its year five days long and its surface temperature above 1,100°F (600°C).

Nevertheless, says Colon, detecting water even on this hellish world is important. "Eventually," she says, "we'll be able to study smaller, Earthlike planets, but if we can pin down the properties of larger planets and perfect our observing techniques, we'll be ready."

 "For the past two or three years, we've felt a growing concern that our efforts to study the composition of exoplanet atmospheres might be stymied," says MIT astronomer Zachory Berta-Thompson, who was not involved in the new research.

The discovery was made using the transit method of spectroscopy, whereby certain elements filter out light that pass through it. So as the star comes between Earth and its star the sliver of light that passes through the atmosphere is looked at and analyized. In principle, atoms and molecules, including H2O, should alter the starlight, imprinting a telltale signature that can be read by powerful telescopes; however in the past this has beend difficult to do on smaller planets.

This method has been previously been done successfully for larger, Jupiter-size exoplanets. But until now, said Jonathan Fraine of the University of Maryland, College Park, lead author of the Nature report, "the light has always been blocked by haze or clouds when we tried to look at smaller planets." That's especially frustrating because planets are more numerous in smaller sizes, and because planets closer in size to Earth are considered more likely to be habitable-and maybe even inhabited.

Using the Hubble, Spitzer, and Kepler Space Telescopes in tandem, the new study finally did manage to pick up water's signature in the starlight passing through HAT-P-11b's atmosphere. It was possible because of the planet's clear skies. Previous attempts ran into problems with the thickness of the atmosphere, and scientists speculate that the heat of this planet.

"In the long run, if we can detect water, methane, carbon monoxide, carbon dioxide, etc., in dozens to hundreds of exoplanet atmospheres of various bulk properties, then we will be able to paint a much clearer picture of how planets form, and, likewise, how Earth formed," lead author Jonathan Fraine, a graduate student at the University of Maryland, told Space.com. "This was just one of the beginning brush strokes to painting the full picture of how planets, as well as ourselves, were formed."

Astronomers will have many, many, many, many^100 more planets to explore, with results still rolling in from NASA's Kepler planet-hunting mission and another huge haul that could come from the planned Transiting Exoplanet Survey Satellite (TESS) mission.

The researchers were comprised a international team out of the University of Maryland, and published their findings in the journal Nature on Wednesday.