Alien Atmospheres: ‘Astronomers using the orbiting 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 show it is possible to measure the chemical makeup of extra-solar planetary atmospheres — and potentially to search for chemical markers of life far beyond Earth.

The Jupiter-sized planet orbits a yellow, Sun-like star called HD 209458 that lies 150 light-years away in the 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…Transit observations by Hubble and ground-based telescopes confirmed that the planet is primarily gaseous, rather than liquid or solid, meaning that it is a gas giant, like Jupiter and Saturn.’ science@NASA