The outer solar system is a fairly quiet place we are assured. Not a lot of meteors or craters on the likes of Pluto and Charon. However, the orbital architecture of Kuiper Belt objects is odd – and it has been suggested they are controled by the gravity of the hypothetical Planet Nine. This is because known objects appear to bunch up tight in what is described as orbital clustering (see image below). Go to https://phys.org/print470495718.html …
.. there is also another paper due in the next issue of Physics Reports. It provides thousands of new computer models of the distant solar system and offers insight into the nature of Planet Nine – if it exists. The authors conclude Planet Nine has a mass about 5 times that of the Earth. It is smaller and closer to the Sun than previously imagined.
At https://phys.org/print470573459.html … Kuiper Belt objects are surprisingly rare – using data from the New Horizons mission spacecraft.