Astronomers at Harvard revealed the discovery of a so-called mega-Earth they are calling Kepler 10c this week. However, they say the planet defies everything they know about how planets are formed and how big certain types of planets can get.

Mega-Earth

Mega-Earth weighs 17 times as much as Earth

Time reports that the newly discovered planet, which they’re calling a “mega-Earth,” is massive compared to the size of our Earth. Kepler 10c is approximately 18,000 miles across, while Earth is only approximately 8,000 miles across. The planet is about 17 times heavier than Earth, and Harvard astrophysicist Dimitar Sasselov calls it “the Godzilla of Earths.”

Astronomers said it’s a surprise that the so-called “mega-Earth” even exists and that they don’t have any idea where it came from. They explained during their press conference that whenever there’s a planet made of rock that’s up to ten times the size of Earth, it begins collecting all the nearby gases because its gravitational pull is so powerful. They added that as planets form, it would be expected that there would be a lot of gas around to pull in, so it’s mystery to them why the planet has so little gas around it when the core is so large, heavy and rocky.

To put this into perspective, Neptune, Saturn, Jupiter and Uranus all have huge rocky cores that are even bigger than Earth. However, the majority of their mass is gas.

Suggested theories leave scientists with questions

Some scientists have ideas about how this may have happened, although they don’t think either of these two possibilities is very likely. One NASA theorist suggested that all the gas could have been gone by the time the Mega-Earth Kepler 10c reached its massive size. He also suggests that it’s possible that the planet was the result of two smaller rocky planets colliding.

Scientists are also puzzled because of when they think the mega-Earth might have formed. They think it was formed during a time when silicon and iron, with silicon being one of the main components of rock, were just not as abundant than they were when the sun was created. Nonetheless, they say Kepler 10c contains a lot of both minerals.

Mega-Earth can’t sustain life

In spite of all the comparisons to Earth, scientists say Kepler 10c can’t actually sustain life. They say the planet’s orbit is only 45 days and that it is so close to its sun that water can’t exist in liquid form on its surface. They also say that while approximately 1% of our Earth’s mass is water, oxygen and other volatile substances, the mega-Earth’s percentage of volatile substances is closer to 10%.