Observations by the NASA/ESA Hubble Space Telescope have come up with a new class of planet, a waterworld enshrouded by a thick, steamy atmosphere. It's smaller than Uranus but larger than Earth.

An international team of astronomers led by Zachory Berta of the Harvard-Smithsonian Center for Astrophysics (CfA) made the observations of the planet GJ 1214b.

"GJ 1214b is like no planet we know of," Berta said. "A huge fraction of its mass is made up of water."

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