Researchers at the Harvard-Smithsonian Center for Astrophysics found something very interesting while searching for planets in the constellation Draco.
Using NASA's Kepler spacecraft, they spotted a giant planet with a diameter of nearly 18,000 miles — that's more than two times as large as Earth.
Scientists named the planet Kepler-10c. According to the release, it "circles a sunlike star once every 45 days" and "is located about 560 light-years from Earth." (Via David A. Aguilar (CfA))
The team was all but convinced the planet was composed of gas because of its massive size.
"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." (Via NASA)
But the astronomers decided to dig a little deeper, observing the planet using the HARPS-North instrument, a tool used to measure a planet's mass. (Via Telescopio Nazionale Galileo)
Lo and behold, they found out the planet isn't gaseous at all — it's a massive rocky planet "weighing 17 times as much as Earth." (Via Harvard-Smithsonian Center for Astrophysics)
Bottom line: It's now being called the "Godzilla of Earths." CfA astronomers say the Kepler system, which includes the rocky Kepler-10c, likely formed about 11 billion years ago, making it an old system with old stars.
Space.com points out an important implication: "The new finding bolsters the idea that old stars could host rocky Earths, giving astronomers a wider range of stars that may support Earth-like alien worlds to study."
The researchers say Kepler-10c is massive enough to trump the previously named super-Earths. Kepler-10c is in a league all its own, lovingly dubbed a mega-Earth.