Astronomers using NASA's Hubble Space Telescope have made the first direct detection and chemical analysis of the atmosphere of a planet outside our solar system. Their unique observations demonstrate it is possible with Hubble and other telescopes to measure the chemical makeup of extrasolar planets' atmospheres and potentially to search for chemical markers of life beyond Earth.
The planet orbits a yellow, Sun-like star called HD 209458, a seventh-magnitude star (visible in an amateur telescope) that lies 150 light-years away in the autumn constellation Pegasus. Its atmospheric composition was probed when the planet passed in front of its parent star, allowing astronomers for the first time ever to see light from the star filtered through the planet's atmosphere.
Lead investigator David Charbonneau of the California Institute of Technology, Pasadena, and the Harvard- Smithsonian Center for Astrophysics, Cambridge, Mass.; Timothy Brown of the National Center for Atmospheric Research, Boulder, Colo.; and colleagues used Hubble's spectrometer (the Space Telescope Imaging Spectrograph, or STIS) to detect the presence of sodium in the planet's atmosphere.
"This opens up an exciting new phase of extrasolar planet exploration, where we can begin to compare and contrast the atmospheres of planets around other stars," says Charbonneau. The astronomers actually saw less sodium than predicted for the Jupiter-class planet, leading to one interpretation that high-altitude clouds in the alien atmosphere may have blocked some of the light. The team's findings are to be published in the Astrophysical Journal.
The Hubble observation was not tuned to look for gases expected in a life-sustaining atmosphere (which is improbable for a planet as hot as the one observed). Nevertheless, this unique observing technique opens a new phase in the exploration of exoplanets, or extrasolar planets, say astronomers. Such observations could potentially provide the first direct evidence for life beyond Earth by measuring unusual abundances of atmospheric gases caused by the presence of living organisms.
(Ed - KICK ASS !)
News source: nasa.gov
