An alien world 'like no planet we know of'

GJ1214b, shown in this artist’s view, is a super-Earth orbiting a red dwarf star 40 light-years from Earth. New observations from the Hubble Space Telescope show that it is a waterworld enshrouded by a thick, steamy atmosphere. GJ 1214b represents a new type of planet, like nothing seen in the solar system or any other planetary system currently known.

Scientists have discovered a new type of alien planet — a steamy waterworld that is larger than Earth but smaller than Uranus.

David A. Aguilar / CfA / NASA / ESA

The standard-bearer for this new class of exoplanet is called GJ 1214b, which astronomers first discovered in December 2009. New observations by NASA's Hubble Space Telescope suggest that GJ 1214b is a watery world enshrouded by a thick, steamy atmosphere.
"GJ 1214b is like no planet we know of," study lead author Zachory Berta of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., said in a statement. "A huge fraction of its mass is made up of water."
Adding to the diversity To date, astronomers have discovered more than 700 planets beyond our solar system, with about 2,300 more "candidates" awaiting confirmation by follow-up observations.
These alien planets are a diverse bunch. Astronomers have found one planet as light and airy as Styrofoam, for example, and another as dense as iron. They've discovered several alien worlds that orbit two suns, like Luke Skywalker's home planet of Tatooine in the "Star Wars" films.
But GJ 1214b, which is located 40 light-years from Earth in the constellation Ophiuchus (The Serpent Bearer), is something new altogether, researchers said.
This so-called " super-Earth " is about 2.7 times Earth’s diameter and weighs nearly seven times as much as our home planet. It orbits a red-dwarf star at a distance of 1.2 million miles (2 million kilometers), giving it an estimated surface temperature of 446 degrees Fahrenheit (230 degrees Celsius) — too hot to host life as we know it.