The impossible solar birth of an Earth-like planet

By Casey Frye, CCNN Writer

sun birthed planet
See how close in size the planet is to ours?

Last month, astronomers discovered a planet called Kepler-78b around 400 lightyears away that was very much like Earth. Not only is it just about the same size as our home planet, researchers also estimated the distant rock has the same basic composition, meaning it’s made up of similar materials like iron and rock.

Besides the fact that it’s not Earth, there are huge differences between Kepler-78b and our planet. The most extreme is the fact that the alien planet is so close to its host star – its version of the Sun – that researchers say there’s a huge chance Kepler-78b’s surface is a swirling pool of molten lava. More surprisingly, according to new reports, the darn thing shouldn’t even exist!

“This planet is a complete mystery,” says astronomer David Latham of the Harvard-Smithsonian Center for Astrophysics (CfA). Why is this? Well, for one, researchers say there’s no possible way the planet could have been formed near the star. At the time of Kepler-78b’s birth, its host star would have been much larger! Since the fiery world’s orbit is so small, that could only mean it formed inside of the star… and that’s just not possible!

To complicate the matter further, its also impossible that Kepler-78b was caught in the star’s gravity. It’s so close, that there’s no way the planetary rock could have just stopped all of a sudden to enter an orbit. Instead, it would’ve been completely sucked into the star! “It couldn’t have formed further out and migrated inward, because it would have migrated all the way into the star. This planet is an enigma,” said CfA astronomer Dimitar Sasselov.

It’s definitely a mystery that has researchers scratching their heads in confusion, but what they do know is this: the star’s gravity will eventually eat up the fiery planet. According to estimates, Kepler-78b has roughly 3 billion years to live.

I hope researchers figure out how the large lava-rock formed before then, and if they do, I’ll be sure to update you as well. Then again, 3 billion years is a long time!

Images courtesy of NASA.