There’s a planet circling a star 560 light years away in the constellation Draco that shouldn’t be there according to what used to pass for conventional wisdom in planetary formation.
Dubbed Kepler-10c because it was initially spotted by the Kepler space telescope, the exoplanet is twice the size of Earth but contains 17 times our planet’s mass. Further investigation by the team at the Telescopio Nazionale Galileo in the Canary Islands determined that Kepler-10c is a rocky world with an atmosphere. It is also believed that it contains water despite its high surface temperature.
This wouldn’t be so shocking if the 11 billion-year-old planet weren't so darn big. Because of its size, this mega-Earth, which is too hot to harbor life as we know it, has already earned the nickname “Godzilla of Earths” by scientists a little too tuned in to what’s playing in the multiplexes.
If Kepler-10c were part of our solar system, we would expect it to conform to the model provided by planetary giants like Jupiter and Saturn. Those giants are composed mostly of gas.
Theoretically, planets of Kepler-10c’s size aren’t supposed to be such solid, rocky specimens. Kepler-10c was formed 3 billion years after the Big Bang, a time on the cosmic scale that is considered too early for planets of its size and density to have formed.
So, scientists are now confronted with the existence of an ancient rocky planet far older and bigger than Earth that should be a gas giant given its mass. There are probably billions more like it that we’ll begin to stumble upon in the coming years.
To say our previous theories of planetary formation are in need of a drastic update is an understatement. Who says there’s nothing new under the sun? Sometimes a planet that defies all expectations is circling that very sun.