NASA announced yesterday that a team of astronomers had detected water vapor on one small planet about the size of Neptune. The researchers, who published their findings in the journal Nature, were able to detect water vapor in the atmosphere of planet HAT-P-11b by looking at the changes in light as it passed in front of its star. They used the Hubble, Spitzer and Kepler telescopes for observations.
As the BBC reports, this is the smallest planet whose atmosphere has been analyzed with this method. Previously, the method was applied only to large gas giants, the size of Jupiter. Smaller planets weren’t large enough or had too many clouds to get good observations. Because HAT-P-11b had a clear, cloudless atmosphere, they were able to get a good look at the composition of the atmosphere: it's 90 percent hydrogen, with a good amount of water vapor thrown in.
“This discovery is a significant milepost on the road to eventually analyzing the atmospheric composition of smaller, rocky planets more like Earth,” John Grunsfeld, assistant administrator of NASA’s Science Mission Directorate, said in a press release. “Such achievements are only possible today with the combined capabilities of these unique and powerful observatories.”
The planet is located in the constellation Cygnus, 124 light years away from earth. The planet orbits its star in just five days (Mercury, by comparison, orbits the sun in 88 days), and has estimated surface temperatures of 1120 degrees Farenheit.