The faraway exoplanet could help provide answers as to why there are hardly any planets with twice the diameter of Earth.

“I was moved that the universe ... planets by seeking gravitational pulls on their stars. But this method was best suited to finding gas giants like Jupiter. To find rocky Earth-size planets ...

a timeline that dwarfs in comparison to our solar system’s 4.6 billion years of age. The astronomers studying the discovery identified these planets were formed by a process called “core ...