A recent study proposes that the solar system once contained a third ice giant planet in addition to Uranus and Neptune. Published in Icarus, the research indicates this extra world may have driven a period of intense orbital instability billions of years ago, reshaping the paths of Jupiter, Saturn, Uranus and Neptune while affecting their moons.
The analysis examined 122 computer simulations of the early solar system that matched current planetary positions. These runs tested scenarios with five or six giant planets, consistent with the Nice Model of planetary migration. Results showed low survival rates for the moon systems of Jupiter and Uranus, below 15 percent in most cases.
Close encounters with Uranus often led to moon collisions rather than ejection, creating debris that later reassembled. Researchers suggest this process could account for the formation of Uranus’s moon Miranda and indicate at least two major disruption events for its satellites. The study notes that further modeling is required to refine these findings on individual moons.
