Kepler-10c (Credit: David A. Aguilar, CfA). A team trained the HARPS-N spectrograph on the Canary Islands’ Telescopio Nazionale Galileo at Kepler-10c for some intensive observation “over two observing seasons” and recently published the resulting data and determinations, which indicate that the planet is actually a rocky world weighing 17 times more than Earth.
This confounds current understanding of planet formation, which tells us that such a massive planet should attract tons of hydrogen gas to itself, transforming it into a gas giant in the mold of Jupiter or Saturn.
It was originally thought that with its observed diameter of 18,000 miles (2.3 times that of Earth), Kepler-10c was likely to be more like a “mini Neptune” composed largely of thick gases. However, the new data indicates that the planet has a dense composition of rocks and other solids.
“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 also implies that astronomers shouldn’t rule out older stars in the search for Earth-like planets, which could mean that potentially habitable worlds could be closer, in the galactic sense, then previously thought.