astroengine writes "Kepler-78b may be an exoplanet notable for being approximately Earth-sized and likely possessing a rocky surface plus iron core, but that's where any similarity to our planet ends. It has an extremely tight orbit around sun-like star Kepler-78, completing one 'year' in only 8.5 hours. It orbits so close in fact that the alien world's surface temperature soars to 2,000 degrees hotter than Earth's. Referring to Kepler-78b as a 'rocky' world is therefore a misnomer — it's a hellish lava world. But this is just a side-show to the real conundrum behind Kepler-78b: It shouldn't exist at all. 'This planet is a complete mystery,' said astronomer David Latham of the Harvard-Smithsonian Center for Astrophysics (CfA) in a press release. 'We don't know how it formed or how it got to where it is today. What we do know is that it's not going to last forever.'"