Astronomers have announced the discovery of carbon dioxide on an alien exoplanet orbiting a star 65 light years from our own system. While the planet, HD 189733b, is a"hot" Jupiter orbiting too close to its parent star to support life, it is remarkable that we have now been able to determine how to discover three of the four major chemical compounds that are indicators of alien life.
" "This is the first detection of carbon dioxide in the atmosphere of an extrasolar planet, which means that three of the Big Four biomarkers for habitable/inhabited worlds have now been seen: water, methane, and now carbon dioxide," explained Alan Boss, a planet-formation theorist at the Carnegie Institution of Washington who was not involved in the finding. "The only one that has not yet been detected is oxygen/ozone."
Boss told SPACE.com that the detections provide "proof of concept" for what astronomers would search for in looking at an Earth-like world. The detection of carbon dioxide, Boss said, was made with a low degree of resolving power, the sort that could be provided by NASA's planned Terrestrial Planet Finder."
The discovery was made by Giovanna Tinetti of University College in London, England, and used a novel technique of measuring the light from the star both when the planet was in front of the star and behind the star, and using the difference to determine what light was coming from the planet and doing a spectral analysis.