spacetoday.net: Astronomers use Hubble to study cloudy exoplanets

Posted: Thu, Jan 2, 2014, 7:45 AM ET (1245 GMT)
GJ 1214b exoplanet illustration, Dec 2013 (NASA)

Observations by the Hubble Space Telescope have allowed astronomers to determine that two relatively nearby exoplanets likely have cloudy atmospheres. In a pair of papers published in this week's issue of the journal Nature, astronomers reported on Hubble spectral observations of the exoplanets GJ 436b and GJ 1214b as they transited their stars as seen from Earth. The Hubble observations of GJ 436b, a planet similar in size to Neptune but in a closer orbit, were featureless, suggesting it has a high cloud layer blocking observations of the lower atmosphere, or an atmosphere free of hydrogen. Observations of GJ 1214b, a super-Earth, were also featureless, but scientists said they had "definitive evidence of high clouds" because they could rule out the presence of non-hydrogen constituents.