This is a fascinating theory on why the planets are out of line with the sun. While it doesn’t prove the existence of Planet Nine, it certainly points in that direction.
The eight major planets still circle the sun in the original plane of their birth. The sun rotates on its own axis, but surprisingly, that spin is tilted: the axis lies at an angle of 6 degrees relative to a line perpendicular to the plane of the planets.
There are a few theories to explain this jaunty slant, including the temporary tug of a passing star aeons ago, or interactions between the magnetic fields of the sun and the primordial dusty disc that formed the solar system. But it is hard to account for why the sun’s spin is aligned the way it is relative to the planets.
Two teams of astronomers have just announced a new explanation: a hypothetical massive planet in the outer solar system could be interfering with all the other planets’ orbits.