Astronomers with the National Aeronautic and Space Administration have discovered a world they didn't think could exist: a rocky planet more than twice as large and 17 times heavier than Earth.

The planet, Kepler-10c, is located about 560 light-years from Earth in the Draco constellation and orbits a sun-like star every 45 days, making it too hot to sustain life as we know it.

The Kepler 10 system also hosts Kepler-10b, the first rocky planet discovered in the Kepler data.

Previous research had measured the far-off planet at 2.3 times the size of the Earth, but to determine its mass, astronomers turned to observations from HARPS North, or the High Accuracy Radial velocity Planet Searcher for the Northern Hemisphere, located at the Telescopio Nazionale Galileo in the Canary Islands.

The new insights about Kepler-10c's mass have left a good deal of theorists scratching their heads because, following long-held beliefs about the dynamics of astral bodies, the existence of such a large rocky body should not be possible.

Scientists thought the enormous gravitational force of a planet as large as Kepler 10c's massive body would form a blanket of gas during its formation, turning the planet into a gas giant the size of Neptune or even Jupiter.

But Kepler-10c is now believed to be solid, composed mainly of rock.

"Just when you think you've got it all figured out, nature gives you a huge surprise -- in this case, literally," Natalie Batalha, Kepler mission scientist at NASA's Ames Research Center in Moffett Field, California, said in a news release.

The new findings about the the planet's solid mass was presented at a meeting of the American Astronomical Society in Boston.

"We were very surprised when we realized what we had found," says astronomer Xavier Dumusque of the Harvard-Smithsonian Center for Astrophysics, who led the analysis using data originally collected by NASA's Kepler space telescope.

Said Batalha: "Isn't science marvelous?"