NASA’s Kepler Mission may be over, but the massive amount of data that the spacecraft collected is still being studied. In fact, new planets are still being discovered every day. One such planet is Kepler-78b in the constellation Cygnus, and according to astronomers, this planet is an enigma and should not exist.
The issue with Kepler-78b is not that it’s Earth-sized, and it's not that it has a similar density to Earth. Those are both good things. The problem lies with the fact that the planet is orbiting way too close to its star, much closer than ever thought possible. Every 8.5 hours, the planet circles its star at a distance of less than one million miles. Current scientific theories state that this should never happen: planets simply don’t form so close to their stars, and Kepler-78b certainly could not have moved there. Its very existence has left scientists confused.
Scientists at the Harvard-Smithsonian Center for Astrophysics studied this new planet with the HARPS-North spectrograph. They worked with a second team of astronomers to confirm their data. Still, Kepler-78b defies explanation. Obviously, we need to tweak our understanding of planet formation and movement. It's turning out that Kepler-78b is part of a new class of small Earth-sized planets that have been recently discovered that orbit their stars in less than 12 hour increments.
Unfortunately, because of its closeness to its star, Kepler-78b is expected to eventually get ripped apart by its star’s gravity and vanish without a trace. Its lifespan? Only about 3 billion years. This means that such a planet could have once graced our solar system, but we wouldn't know about it because it would have suffered a similar fate.