A diagram shows the five recently-discovered moons of Jupiter that scientists need to name. (Image: © Roberto Molar Candanosa/Carnegie Institution for Science)
My guess is, any planetary bodies discovered beyond Pluto will be moving in retrograde (or at the very least, at a substantial angle to the ecliptic), which is diagnostic of capture. This is analogous to the many small moons of Jupiter, and for that matter, Neptune's moon Triton.
A diagram shows the five recently-discovered moons of Jupiter that scientists need to name. (Image: © Roberto Molar Candanosa/Carnegie Institution for Science)
That’s what I am thinking plus we know our solar system had many close encounters over the life of it’s existence
