http://www.sciencedaily.com/releases/20 ... ience+News)
Jan. 8, 2014
"We were surprised to learn that planets only a few times bigger than Earth are covered by a lot of gas," said Lithwick, an assistant professor of physics and astronomy at Northwestern's Weinberg College of Arts and Sciences.
Earth-mass exoplanet is no Earth twin
Gaseous planet challenges assumption that Earth-mass planets should be rocky.
http://www.nature.com/news/earth-mass-e ... in-1.14477
06 January 2014
Astronomers have discovered an extrasolar planet with the same mass as Earth, but the resemblance ends there. Not only is the planet too warm for liquid water to exist on its surface, but it also has a radius 60% larger than Earth, suggesting a vast, puffy atmosphere of hydrogen and helium.
“You’ve got a very small planet that is probably not rocky at all, and that’s frightening,” says Jacob Bean, an astrophysicist at the University of Chicago in Illinois.
What is scary, he says, is how the finding challenges the assumption that an Earth-mass exoplanet would have an Earth-like composition. With its thick atmosphere, the exoplanet is more like a scaled-down Neptune or Uranus, he notes.