Scientists have reported the first conclusive discovery of water vapor in the atmosphere of an exoplanet, or a planet beyond our solar system.

This artist's impression shows a gas-giant exoplanet transiting across the face of its star. Infrared analysis by NASA's Spitzer Space Telescope of this type of system provided the breakthrough.

The planet, HD 189733b, lies 63 light-years away in the constellation Vulpecula. It was discovered in 2005 as it transited its parent star, dimming the star's light by some three percent.

JPL manages the Spitzer Space Telescope mission for NASA's Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center at the California Institute of Technology, Pasadena. JPL is a division of Caltech. Spitzer's infrared array camera was built by NASA's Goddard Space Flight Center, Greenbelt, Md. The instrument's principal investigator is Giovanni Fazio of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass.

For more information about Spitzer, visit http://www.spitzer.caltech.edu/spitzer and http://www.nasa.gov/spitzer.