Planet Nine estimated mass of ten Earths, a diameter two to four times that of Earth, and an elongated orbit lasting 10,000 - 20,000 years. Batygin and Brown suggest that Planet Nine could be the core of a primordial giant planet that was ejected from its original orbit by Jupiter during the genesis of the Solar System. Others have proposed that the planet was captured from another star, is a captured rogue planet, or that it formed on a distant orbit and was pulled into an eccentric orbit by a passing star. As of 2018, efforts have failed to directly observe Planet
Five-planet Nice model in 2011 after numerical models indicated that this is more likely to reproduce the current Solar System. The following is a version of the five-planet Nice model that results in a late instability and reproduces a number of aspects of the current Solar System. The early Solar System may have evolved differently, however, with the instability occurring soon after the dissipation of the gas nebula, or with the giant planets beginning in another resonance chain. The Solar System ends its nebula phase with Jupiter, Saturn, and the three ice giants in a 3:2, 3:2, 2:1, 3:2 resonance chain with semi-major