Methane detected on distant planet

Scientists have detected the presence of methane on a faraway planet, the first time an organic molecule has been spotted in the atmosphere of a planet outside our solar system.

Astronomers using the Hubble Space Telescope detected methane and confirmed the presence of water vapour on a planet called HD 189733b, a hot Jupiter-sized planet about 63 light years from Earth.

The presence of both water and organic molecules — molecules containing carbon-hydrogen bonds — are features scientists look for in their attempts to find planets capable of supporting life.

Though HD 189733b is not a candidate for hosting life — its atmospheric temperatures can reach over 900 degrees C — the observations could inform further attempts to understand the chemical makeup of more suitable planets.

Using near-infrared sensors on Hubble, the team from the California Institute of Technology's Jet Propulsion Laboratory and the University College of London observed the planet while it passed in front of its parent star.

HD 189733b orbits a star in the constellation Vulpecula much closer than Mercury does to our sun. Its large size and close proximity to its star have made it in an ideal planet for studying.

The researchers were able to detect methane and confirm an earlier report of water vapour, but were unable to find carbon monoxide, which they expected to be abundant in the atmosphere.

The scientists suggest this could have something to do with the unique processes at work in the planet's atmosphere.

The planet is tidally locked to its star the way our moon is to Earth, meaning one side of the planet is always facing the star. The warm spot of the planet facing the star had a temperature of 930 C, while the planet's dark side had a temperature of 650 C.

HD 189733b is one of more than 270 planets to be discovered outside our solar system.

The findings will appear in the Thursday edition of the journal Nature.