BOSTON — Scientists have just discovered the "Godzilla of Earths" — a new type of huge and rocky alien world about 560 light-years from Earth.
Dubbed a "mega-Earth," the exoplanet Kepler-10c is 17 times as massive as our planet and circles a sunlike star in the constellation Draco. The mega-Earth is rocky and also bigger than "super-Earths," which are a class of planets as much as 10 times as massive as Earth.
Theorists weren't sure that a world like the newfound exoplanet could exist. Scientists thought that planets of Kepler-10c's size would be gaseous, collecting hydrogen as they grew and turning into Jupiter-type worlds. However, researchers have now found that the newly discovered planet is rocky, Christine Pulliam, a spokeswoman with the Harvard-Smithsonian Center for Astrophysics, wrote in a statement announcing the find. [Gallery: The Strangest Alien Planets Ever Found]
"This is the Godzilla of Earths!" the CfA's Dimitar Sasselov, director of the Harvard Origins of Life Initiative, said of Kepler-10c in a statement. "But unlike the movie monster, Kepler-10c has positive implications for life."
The discovery of Kepler-10c was presented on Monday here at the 224th American Astronomical Society meeting.
The mega-Earth orbits its parent star once every 45 days. Kepler-10c is probably too close to its star to be hospitable to life, and it isn't the only planet orbiting the yellow star. Kepler-10 also plays host to a "lava world" called Kepler-10b that is three times the mass of Earth and speeds around its star in a 20-hour orbit.
NASA's Kepler space telescope first spotted Kepler-10c, but it wasn't able to tell whether the world was gaseous or rocky. CfA astronomer Xavier Dumusque and his team used the HARPS-North instrument on the Telescopio Nazionale Galileo in the Canary Islands to measure Kepler-10c's mass. They found that the planet is, in fact, rocky and not a mini-Neptune.
Scientists think the Kepler-10c system formed less than 3 billion years after the Big Bang. The system's early formation suggests that, although the materials were scarce, there were enough heavy elements like silicon and iron to form rocky worlds relatively early on in the history of the universe, according to the CfA.
"Finding Kepler-10c tells us that rocky planets could form much earlier than we thought," Sasselov said. "And if you can make rocks, you can make life."