Past the Kuiper Belt (seen right here) lies the theorised Oort cloud, the place an additional planet may very well be hiding
NASA
Our photo voltaic system may very well be hiding an additional planet in its outermost reaches. It’s attainable {that a} big planet lurks within the Oort cloud, which begins a whole bunch of billions of kilometres past Pluto and has usually been thought-about the area of comets.
Most multi-planet techniques, particularly these with big worlds like our personal photo voltaic system, bear what known as a dynamical instability in some unspecified time in the future of their lifetime, whereby the planets …