Astronomers announced that they have discovered a new type of planet – a rocky world weighing 17 times as much as Earth. Theorists believed such a world couldn’t form because anything so hefty would grab hydrogen gas as it grew and become a Jupiter-like gas giant. This planet, though, is all solids and much bigger than previously discovered “super-Earths,” making it a “mega-Earth.”
Scientists say the new planet may have “profound implications for the possibility of life” on extra-solar planets, according to a press release from the Harvard-Smithsonian Center for Astrophysics. They announced the finding in a talk at the American Astronomical Society meeting in Boston.
Researchers have always thought Mega-Earths were impossible since any planets that big would attract hydrogen gas, forming a gas planet like Jupiter.
“We were very surprised when we realized what we had found,” says astronomer Xavier Dumusque of the Harvard-Smithsonian Center for Astrophysics (CfA), who led the data analysis and made the discovery.
“This is the Godzilla of Earths!” adds CfA researcher Dimitar Sasselov, director of the Harvard Origins of Life Initiative. “But unlike the movie monster, Kepler-10c has positive implications for life.”
Kepler-10c was originally spotted by NASA’s Kepler Space Telescope in May 2011. The planet lies in the constellation Draco, about 564 light-years away, and circles its host star, Kepler-10, once every 45 days. The system also hosts another previously known exoplanet, Kepler-10b.
Kepler-10c was known to have a diameter of about 29,000 km, about 2.3 times as large as Earth. This suggested it fell into a category of planets known as mini-Neptunes.
The Kepler-10 system is about 11 billion years old, which means it formed less than 3 billion years after the Big Bang.
“Finding Kepler-10c tells us that rocky planets could form much earlier than we thought. And if you can make rocks, you can make life,” Dr Sasselov concluded.