In 2009, NASA launched the Kepler space observatory to discover Earth-size planets orbiting other stars. For four and a half years, Kepler photographed a small 10-by-10 degrees section of the sky, taking snapshots each minute. "This is a goldmine of data, and we won’t see anything quite like it in the foreseeable future," explains Rasmus Handberg from the Stellar Astrophysics Centre at Aarhus University, Denmark.