Will Neptune and Pluto ever collide in their orbits?

Diagrams of the Solar System give the impression that the orbits of Neptune and Pluto cut right across each other, and textbooks even state that Pluto crossed the orbit of Neptune in February 1999. Yet in reality the two planets can never get close to colliding, for two reasons. read more

Furthermore, the closest Pluto ever comes to Neptune is about 2 billion km. It is possible that gravitational effects so subtle and far in the future could produce changes in the orbit of Pluto that it could collide with Neptune. However, this would be at least 1 million years into the future, and likely even longer. read more

It is true that the orbits of Neptune and Pluto cross, with the two objects swapping positions in the Solar System. Despite this, however, there is no chance of them colliding. read more