Researchers report in tomorrow's issue of Nature that a 40-minute gaze with the Hubble Space Telescope last May [2007] has revealed methane in the atmosphere of HD 189733b, a Jupiter-size planet orbiting close to its very bright parent star located 63 light-years away. The observation also confirmed last year's discovery by the Spitzer Space Telescope of water vapor in the planet's atmosphere (see: ScienceNOW, 11 July 2007).

ESA calls this a breakthrough [that] is an important step in eventually identifying signs of life on a planet outside our Solar System.

Science/AAAS News:

Astronomers have detected the organic molecule methane in the atmosphere of an extrasolar planet for the first time and have confirmed earlier observations of water vapor. Alas, the findings don't come close to suggesting that life has emerged on this other world, but they do contribute to a growing body of data about planetary evolution outside our own solar system.

Co-author Mark Swain of NASA's Jet Propulsion Laboratory in Pasadena, California, emphasized that HD 189733b is far too hot--average atmospheric temperature about 1000°C--to support life as we know it. But the presence of methane raises intriguing questions, he said, because the high temperature should have sequestered all of the carbon in the planet's atmosphere in the form of carbon monoxide (CO), not methane (CH4). That suggests a currently unknown chemical process is at work, he said.