In August, researchers identified an exoplanet with an extremely brief orbital period: The team found that Kepler 78b, a small, intensely hot planet 400 light-years from Earth, circles its star in just 8.5 hours — lightning-quick, compared with our own planet's leisurely 365-day orbit. From starlight data gathered by the Kepler Space Telescope, the scientists also determined that the exoplanet is about 1.2 times Earth's size — making Kepler 78b one of the smallest exoplanets ever measured.