for National Geographic News
A high-powered space telescope has caught what researchers are saying is the first clear sign of water on a planet outside our solar system.
The planet, known as HD 189733b, is a gas giant similar to Jupiter.
But this huge planet, which orbits a star about 63 light-years away, hugs its host much closer and broils at more than 1,300°F (700°C).
This means that the planet's water is all in the form of superheated steam. Liquid water—and thus life as we know it—couldn't exist there.
The new findings solve a puzzle that arose earlier this year, when two previous studies failed to find water of any form on these so-called hot Jupiters.
Both of those studies used NASA's Spitzer Space Telescope to examine HD 189733b and a similar world, HD 209458b, but found no trace of water.
"We were expecting to have a non-negligible amount of water" on these planets based on theories of how hot Jupiters form, said lead author Giovanna Tinetti, a European Space Agency fellow at the Institute d'Astrophysique de Paris in France.
Also using Spitzer but employing a different method, Tinetti and colleagues were able to see that HD 189733b has water after all.
"It's quite exciting to see that theory and measurements are going in the same direction," said Tinetti, whose results will appear tomorrow in the journal Nature.
More than 200 planets orbiting other stars, dubbed exoplanets, have been cataloged so far, and researchers have hinted that many more might exist.
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