Artificial intelligence predicts which planetary systems will survive

How do planetary systems--like our solar system or multi-planet systems around other stars--organize themselves? Of all of the possible ways planets could orbit, how many configurations will remain stable over the billions of years of a star's life cycle? Rejecting the large range of unstable possibilities--all the configurations that would lead to collisions--would leave behind a sharper view of planetary systems around other stars, but it's not as easy as it sounds. "Separating the stable from the unstable configurations turns out to be a fascinating and brutally hard problem," said Daniel Tamayo, a NASA Hubble Fellowship Program Sagan Fellow in astrophysical sciences at Princeton. To make sure a planetary system is stable, astronomers need to calculate the motions of multiple interacting planets over billions of years and check each possible configuration for stability--a computationally prohibitive undertaking.