Has the solar system lost two of its planets?

The solar system may once have been far more crowded than it is today. Billions of years ago, beyond Saturn’s orbit, there were likely one or two additional ice giants orbiting the Sun in compact, unstable paths alongside Uranus and Neptune. These giant planets repeatedly passed close to one another, disrupted the orbits of moons, and may even have played a role in tilting Uranus’s axis. Eventually, the gravitational interactions became so intense that one or two of these worlds were ejected from the solar system and became rogue planets drifting through the darkness of interstellar space.