Scientists spot organic molecule on distant planet

By Will Dunham

WASHINGTON (Reuters) - An organic molecule has been spotted for the first time in the atmosphere of a planet outside our solar system, a key step toward possibly finding signs of life on a distant world, scientists said.

Astronomers using the Hubble Space Telescope found methane in the atmosphere of a planet called HD 189733b, which is about the size of Jupiter and is 63 light-years from Earth, they said in research published on Wednesday in the journal Nature.

Organic molecules contain carbon-hydrogen bonds and can be found in living things. Methane, for instance, is found in natural gas and cattle belches.

But the scientists were quick to point out that this distant planet -- with atmospheric temperatures around 1,800 degrees Fahrenheit (1,000 degrees Celsius) -- is not thought to be a candidate for hosting any form of life.

"For this specific planet we observed, methane cannot be produced biologically," Giovanna Tinetti of the University College London, one of the researchers, said by e-mail.

"It's highly unlikely that cows could survive here," Tinetti joked.

"The idea is to repeat the same kind of observations in the future for planets which are less hostile to the development and evolution of life," she added.

HD 189733b is one of more than 270 planets to be discovered orbiting stars other than our sun -- called extrasolar planets. It is a "hot Jupiter" type, similar to the gas giant Jupiter in our solar system but reaching scorching temperatures because they orbit so closely to their stars.