December 01, 2010 PASADENA, Calif. -- A team of astronomers,
including two NASA Sagan Fellows, has made the first
characterizations of a super-Earth's atmosphere, by using a
ground-based telescope. A super-Earth is a planet up to three
times the size of Earth and weighing up to 10 times as much. The
findings, reported in the Dec. 2 issue of the journal Nature,
are a significant milestone toward eventually being able to
probe the atmospheres of Earth-like planets for signs of life.
The team determined the planet, GJ 1214b, is either blanketed
with a thin layer of water steam or surrounded by a thick layer
of high clouds. If the former, the planet itself would have an
icy composition. If the latter, the planet would be rocky or
similar to the composition of Neptune, though much smaller.
"This is the first super-Earth known to have an atmosphere,"
said Jacob Bean, a NASA Sagan Fellow and astronomer at the
Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass.
"But even with these new measurements, we ca