Did a rogue planet reshape our solar system?

The giant planets weren’t always where we find them today. Jupiter, Saturn, Uranus and Neptune formed in a more compact configuration and later underwent a violent reshuffling that scattered them to their current positions. Exactly what triggered this chaos remains uncertain, but researchers at the Laboratoire d’Astrophysique de Bordeaux and the Planetary Science Institute now propose a close encounter with a wandering substellar object during the sun’s youth.