Mega-Earth – A New Discovery

‘The Godzilla of Earths’ is what they’re calling a giant, rocky planet that was recently found. Originally, researchers thought that a giant rocky planet could not exist. But the discovery of this planet, coming in at 17 times the mass of the Earth and having a rocky surface, was enough to change their minds. They call it the ‘Mega-Earth’.

The proper name for the Mega-Earth is Kepler-10c. It orbits the 11 billion year old star named Kepler-10, which is 560 light years away from the Earth. One light year is about 9 and a half trillion kilometres! It is 2.3 times the size of Earth. But the mass is 17 times the mass of our home planet. This proves that this exo-planet is extremely dense. This can only mean one thing: this Mega-Earth is made of rock. This goes against how we think planets are formed. According to our theories, no rocky world should get that huge. Mega-Earth orbits its star much closer than Earth orbits its star, which is the Sun. Its year is 45 days long, while our year is 365 days long.

A weird thing about the Mega-Earth is this: most of the atoms in a newborn star are hydrogen. This is the lightest chemical element. Earth has no hydrogen in its atmosphere, because our planet is too light to keep it around. Jupiter and its cousins, though, are mostly made of hydrogen and hydrogen compounds. Basically, big planets have a lot of hydrogen. Since it’s as massive as Neptune, Kepler-10c could have kept a thick atmosphere of hydrogen, but it doesn’t seem to have one. Whether that’s because it’s too close to its star or not is another question.

The really cool thing about the discovery of Kepler-10c (Mega-Earth) is that even though Kepler-10c is too hot to support human life, there could be other planets out there like this ‘Godzilla of Earths’ that could. More on this issue can be seen here, in a Bloomsberg broadcast about the recent discovery. Sara Seager can also be found on this TED talk, all about exo-planets.

So it is clear that the discovery is pretty exciting news, and will continue to spark our interest into life beyond Earth. This discovery and every other discovery bring us even closer to understanding how planets form in all their variety.

David Fox