spacetoday.net: Hubble finds carbon dioxide on exoplanet

Posted: Wed, Dec 10, 2008, 7:12 AM ET (1212 GMT)
Hubble illustration of exoplanet HD 189733b (NASA)

Astronomers using the Hubble Space Telescope have detected evidence of carbon dioxide in the atmosphere of an extrasolar planet, a step forward in the search for evidence of life. Hubble's near infrared camera and spectrometer studied light from HD 189733b, a "hot Jupiter" extrasolar planet closely orbiting a star 63 light-years away. Because of the orientation of the planet's orbit, the planet passes behind the star as seen from Earth, allowing astronomers to subtract light from just the star itself from times the star and planet are both in view, thus allowing astronomers to measure the infrared light emitted from the planet's hot interior. That light contained the spectral signature of carbon dioxide absorbing specific wavelengths of light as it passed through the planet's atmosphere. While this planet is thought to be far too hot to support life, but demonstrates the ability to detect this gas for other, more promising planets.