Astronomers Find a New Type of Planet: The “Mega-Earth”


NASA and the Harvard-Smithsonian Center for Astrophysics just made a discovery about a giant rocky planet named Kepler-10c.

Kepler-10c inhabits a constellation called Draco, which is about 560 light-years from Earth. It orbits a sun-like star once every 45 days.

Kepler-10c, as it had been named, had a previously measured size of 2.3 times larger than Earth but its mass was not known until now. The team used the HARPS-North instrument on the Telescopio Nazionale Galileo in the Canary Islands to conduct follow-up observations to obtain a mass measurement of the rocky behemoth.

The discovery shows that Kepler-10c is likely made of rock and other dense solids — something astronomers thought was impossible for a planet this size.

NASA reported that worlds such as this were not thought possible to exist. The enormous gravitational force of such a massive body would accrete a gas envelope during formation, ballooning the planet to a gas giant the size of Neptune or even Jupiter. However, this planet is thought to be solid, composed primarily of rock.

“Just when you think you’ve got it all figured out, nature gives you a huge surprise — in this case, literally,” Kepler mission scientist at NASA’s Ames Research Center Natalie Batalha said in a statement. “Isn’t science marvelous?”

NASA and the Harvard-Smithsonian Center for Astrophysics announced their findings about Kepler-10c on Tuesday saying that scientists are confounded by the rocky mass.

The new findings have some discussing the possibility of extraterrestrial life. 

“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,” says Sasselov.

This research implies that astronomers shouldn’t rule out old stars when they search for Earth-like planets. And if old stars can host rocky Earths too, then we have a better chance of locating potentially habitable worlds in our cosmic neighborhood.

The HARPS-N project is led by the Astronomical Observatory of the Geneva University (Switzerland). The National Institute for Astrophysics (INAF, Italy) has agreed to provide 80 observing nights per year over five years to use HARPS-N coupled to the TNG. The U.S. partners are the Harvard-Smithsonian Center for Astrophysics and the Harvard University Origins of Life Initiative; and the UK partners are the Universities of St. Andrews and Edinburgh, and the Queens University of Belfast.