For the first time, astronomers using the Hubble Space Telescope have directly detected another planet’s atmosphere and its chemical composition.
With this breakthrough, researchers have demonstrated that it is possible, using Hubble and other Earth bound telescopes, to measure the chemical makeup of extrasolar planet atmospheres and to potentially search for chemical markers of life beyond Earth.
The planet orbits a yellow, Sun-like star called HD 209458, which 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.
“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 lead investigator David Charbonneau of the California Institute of Technology – Pasadena.
Previous transit observations by Hubble and ground-based telescopes confirmed that the planet is primarily gaseous, rather than liquid or solid, because it has a density less than that of water. (The Earth, a rocky rather than a gaseous planet, has an average density five times that of water.) Based on those observations, scientists determined the planet is a gas giant, like Jupiter and Saturn.
You can read more about the planet at NASA’s website here.