By Xinhua
London : Scientists have found the organic compound methane for the first time in the atmosphere of a planet outside our Solar System, orbiting a star some 63 light years away from the Earth.
The discovery, made by Giovanna Tinetti from University College, London, and Mark Swain and Gautam Vasisht from NASA’s Jet Propulsion Laboratory in Pasadena, California, was unveiled in the journal Nature available on Wednesday.
The scientists found the signature of methane in the planet’s atmosphere using the Hubble Space Telescope, the Nature said.
The scientists detected the gas in the atmosphere of a Jupiter-sized planet known as HD 189733b, located 63 light years from the Earth, in the constellation Vulpecula — the little fox. The planet orbits closer to the parent star in its Solar System than Mercury does in our own and temperatures there reach 900 degrees Celsius.
The observations were made as the planet passed in front of its parent star, as viewed from Earth. As the star’s light passed briefly through the planet’s atmosphere, the gases imprinted their chemical signatures on the transmitted light.
A method known as spectroscopy, which splits light into its components, revealed the chemical “fingerprint” of methane.
The scientists also confirmed a previous discovery made by NASA’s Spitzer Space Telescope that the atmosphere of HD 189733b also contains water vapor. But they said the planet is far too hot to support life.
It shows that Hubble, Spitzer and a new generation of space telescopes yet to be launched can detect organic molecules on other extrasolar planets using spectroscopy, the scientists said.
Tinetti said the technique could eventually be applied to extrasolar planets that appear more suitable for life than HD 189733b.
The key to this search is the so-called “Goldilocks zone,” an area of space in which a planet is “just the right distance” from its parent star so that its surface is not-too-hot or not-too-cold to support liquid water.
Methane, made up of carbon and hydrogen, is the simplest possible organic compound, which under certain circumstances, can play a key role in prebiotic chemistry — the chemical reactions considered necessary to form life.