... Observing . ... Water vapor on an exoplanet . Using the Spitzer Space Telescope, astronomers find signs of water on a "hot Jupiter." ... A scorching-hot gas planet beyond our solar system is steaming up with water vapor, according to new observations from NASA's Spitzer Space Telescope. ... Astronomers had predicted that planets of this class, termed "hot Jupiters," would contain water vapor in their atmospheres. ... Only registered members of Astronomy.com are allowed to comment on this article. ...