spacetoday.net: Spitzer detects light from exoplanets

Posted: Tue, Mar 22, 2005, 6:59 PM ET (2359 GMT)
Exoplanet infrared observation illustration (NASA)

Astronomers announced Tuesday that they have seen for the first time light coming directly from two extrasolar planets. In separate studies, astronomers reported that they were able to detect infrared light from two exoplanets, HD 209458b and TrES-1, using NASA's Spitzer Space Telescope, a space-based infrared observatory. They were able to distinguish the light coming from the exoplanets from that coming from their parent stars by observing the solar systems both when the planet and star were visible, and also when the planet's orbit took it behind the star, allowing them to subtract out the light of the star alone in order to detect the planet's own infrared emissions. The observation showed that the two exoplanets, both "hot Jupiter" gas giants that orbit very close to their stars, have atmospheric temperatures of at least 1,000 kelvins. Future observations should allow scientists to be able to study the composition and dynamics of the exoplanets' atmospheres.