Earth-mass exoplanet is no Earth twin

@article{Cowen2014EarthmassEI,
  title={Earth-mass exoplanet is no Earth twin},
  author={R. Cowen},
  journal={Nature},
  year={2014}
}
Gaseous planet challenges assumption that Earth-mass planets should be rocky. 

References

Kepler researchers are now awaiting NASA's decision on other uses for the craft (See "NASA ponders Kepler's future"). A final verdict is