Some researchers believe that ‘Planet 9’ exists because of the way certain space phenomena, known as Trans-Neptunian Objects (TNOs), behave. Is there a real Planet 9, and if so, what is its origin and significance?

There is a Planet 9 there. It is a kind of condensed matter object that is more of a star‑like origin, and so it is causing a perturbation of motion of other objects because of its gravitational influence but is not emitting radiation in the visible wavelengths, and this makes it very difficult to observe. It is a remnant of the creation of the solar system itself and is an ordinary object in terms of the many types of bodies within the universe. It has no particular metaphysical or scientific significance, or history with humanity or extraterrestrial civilizations, as some have conjectured. It is simply a natural object with seemingly unusual characteristics, but these have prosaic explanations.