NASA has been discovering one exoplanet after another these days, but its scientists have to look a lot closer if they want to see more details, such as the planets' color or whether they have water. That's exactly what the agency did while observing HAT-P-11b -- by combining the power of three space telescopes, scientists have found clear skies and water vapor on the atmosphere of the Neptune-sized exoplanet. NASA observed the distant world while it was crossing its solar system's sun using one of Hubble's wide field cameras. Water vapor typically absorbs starlight during that process, and it's that light that reaches our telescopes. In order to confirm whether it's actually water vapor (mixed with hydrogen gas and other molecules), the scientists compared Hubble's data to visible-light data collected by Kepler and Spitzer light data taken at infrared wavelengths.
To note, this isn't the first time scientists found water vapor on exoplanets. But, they were all more akin to the size of Jupiter, since it's tough observing smaller ones like this from afar, especially since most of them seem to have cloudy atmospheres. This particular discovery gives NASA hope that it can work its way down to even smaller planets, until it can effectively observe Earth-sized rocky worlds in other solar systems.