Imagine a planet In the UK there was a recent series on “The Planets” by Brian Cox - one of the things I learnt was how a large has giant had migrated over tim

Imagine a planet In the UK there was a recent series on “The Planets” by Brian Cox - one of the things I learnt was how a large has giant had migrated over time from the outer solar system to the inner and back out to the outer. That type of event have caused a slingshot to accelerate a planet like Venus into a highly elliptical orbit, one which might be further accelerated by other planets to a point where it reached escape velocity - especially if combined with large collisions. This would happen in the same way the voyagers gained speed as it flew past the gas giants in the 80s. It’s unlikely, but there are a lot of solar systems and a lot of planets. Predicting the location of a given rogue planet would be like predicting the position if a tractor in a given field in Nebraska. However once you see the tractor is there you can start to predict how it got there.