A scorching-hot gas planet beyond our solar system is steaming up with water vapour, according to new observations from Nasa’s Spitzer Space Telescope. The planet, called HD 189733b, swelters as it zips closely around its star every two days or so.
Astronomers had predicted that planets of this class, termed “hot Jupiters”, would contain water vapour in their atmospheres, but finding solid evidence for this has been slippery. These latest data are the most convincing yet that hot Jupiters are also “wet”.
“We’re thrilled to have identified clear signs of water on a planet that is trillions of kilometres away,” said Giovanna Tinetti, a European Space Agency fellow at the Institute d’Astrophysique de Paris in France. Although water is an essential ingredient to life as we know it, wet and hot Jupiters are not likely to harbour any creatures. Previous measurements from Spitzer indicate that HD 189733b is a fiery 1 000 Kelvin (727 degrees Celsius) on average.
Ultimately, astronomers hope to use instruments like those on Spitzer to find water on rocky, habitable planets like Earth. “Finding water on this planet implies that other planets in the Universe, possibly even rocky ones, could also have water,” said coauthor Sean Carey of Nasa’s Spitzer Science Centre at the California Institute of Technology in Pasadena.