GJ1214b , shown in this artist's conception, is a super-Earth orbiting a red dwarf star 40 light-years from Earth. New observations from NASA's Hubble Space Telescope show that it is a waterworld enshrouded by a thick, steamy atmosphere. GJ1214b therefore represents a new type of world, like nothing seen in our solar system or any other planetary system currently known. Credit: David A. Aguilar (CfA)

Astronomers will most likely find many more similar exotic ocean worlds. "To me, it proves that there are many planets with liquid water, because if there's one like this, it could have been a bit further from the star and then the temperature would have been right," Frederic Pont said. 

Another similar planet is dubbed GJ1214b. The planet is located in the direction of the constellation Ophiuchus, and just 40 light-years from Earth. 

Our solar system contains three types of planets: rocky, terrestrial worlds (Mercury, Venus, Earth, and Mars), gas giants (Jupiter and Saturn), and ice giants (Uranus and Neptune). Planets orbiting distant stars come in an even wider variety, including lava worlds and "hot Jupiters." 

GJ1214b is different. It represents a brand new classification of planet: a veritable world of H2O, encased within a thick atmosphere of water vapor. 

The internal structure of GJ1214b would be very different than our world. 

"GJ1214b is like no planet we know of," explained astronomer Zachory Berta , who led the team that revealed the exoplanet's secret. "A huge fraction of its mass is made up of water." 

"Based on our observations, this atmosphere would likely consist of more than 50% water by mass," write the researchers in the paper describing their findings. 

GJ1214b's density is close to just 1.9 grams per cubic centimeter. Water has a density of 1 g/cm3. The fact that Earth's average density is 5.5 g/cm3 suggests that GJ1214b is harboring a lot more water than Earth and much less rock. 

But despite its hydrous nature, GJ1214b would still be inhospitable to human life, due primarily to the fact that its proximity to its sun gives it an estimated surface temperature in excess of 230 degrees Celsius. 

"The high temperatures and high pressures would form exotic materials like 'hot ice' or 'superfluid water.'" explained Berta, "substances that are completely alien to our everyday experience." 

What more exotic alien worlds are out there? Only time can tell. 

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