How the orbits of the giant planets changed

This video simulates how the orbits of our solar system's giant planets may have changed since their births. The simulation includes two extra Uranus and Neptune-sized ice giants, and the black points represent Kuiper Belt objects like Pluto that tugged the tightly packed planets apart. In the process, the extra ice giants are thrown out of the solar system. The simulation builds upon the Nice model, named after the city in France where it was developed. Credit: Matt Clement, Carnegie Institution for Science