On Monday, NASA announced that one of its spacecraft had spotted the smallest planet ever discovered outside of our own solar system. It is also the first known planet outside this solar system to be made completely of solid material. These are called rocky planets. (Earth is a rocky planet too.)
The planet has been named Kepler-10b, because it was found by the Kepler spacecraft. Because of its size and the fact that it is "rocky," Kepler-10b might've contained water or even life of some kind—if it was the correct distance from the star it orbits (as Earth orbits the Sun). However, NASA scientists say the planet is much too close to its star, so it is too hot for water or life.
Earth's diameter (distance from one side to the other through our planet's center) is about 7,926 miles. Kepler-10b's diameter is about 1.4 times that distance. What is Kepler-10b's diameter?