Planet Nine?

Planet Nine is a hypothetical world about 10 times more massive than Earth.

The planet might be hiding behind Neptune.

It might be another 1,000 years before we can see it.

In October 2017, NASA released a statement saying that Planet Nine may be 20 times further from the Sun than Neptune is.

In the hunt for Planet Nine, scientists have found 12 new moons around Jupiter.

In the Oct. 2017 statement, Caltech planetary astrophysicist Konstantin Batygin, said that there 

"five different lines of observational evidence" 

that point to the existence of the planet.

Six known objects in the Kuiper Belt, all of which have elliptical orbits that point in the same direction.
The orbits of the objects are all tilted the same way.
Computer simulations that show there are more objects "tilted with respect to the solar plane."
Planet Nine could be responsible for the tilt of the planets in our solar system.
Some objects from the Kuiper Belt orbit in the opposite direction from everything else in the solar system.