Astronomers have discovered a hot Earth-size planet so close to its star that a year on that exoplanet lasts just 8.5 hours, making it one of the fastest alien planets ever seen.
The small orbital period — one of the shortest ever discovered for an alien planet among the worlds discovered by NASA's Kepler Space Telescope — means the planet is far outside what is considered the habitable zone of its star, where liquid water, and maybe life, could exist. In fact, scientists have described the new world as a so-called "lava planet."
The find, however, excites astronomers because the host star of the planet, called Kepler-78b, is bright enough for other telescopes to spot the world. This is a relieving note for the research team given that the Kepler Space Telescope's prime exoplanet mission officially ceased Thursday (Aug. 15), scientists said. The spacecraft had to cut its prime planet-hunting mission short when two of its orientation-controlling reaction wheels failed.
Kepler-78b is about 100 times closer to its star than the Earth is to the sun, and orbiting in a star system that is about 750 million years old — about six times younger than the solar system. The planet's surface bakes at an iron-melting temperature somewhere between 3,680 degrees Fahrenheit (2,026 degrees Celsius) and 5,120 degrees Fahrenheit (2,826 degrees Celsius).