Planet X, if it exists, is based on evidence of the orbital parameters on inner planets and the tilt of the Sun.
As yet it is still hypothetical and the research continues.
http://solarsystem.nasa.gov/planets/planetx
Caltech researchers have found evidence suggesting there may be a "Planet X" deep in the solar system. This hypothetical Neptune-sized planet orbits our sun in a highly elongated orbit far beyond Pluto. The object, which the researchers have nicknamed "Planet Nine," could have a mass about 10 times that of Earth and orbit about 20 times farther from the sun on average than Neptune. It may take between 10,000 and 20,000 Earth years to make one full orbit around the sun.
"The possibility of a new planet is certainly an exciting one for me as a planetary scientist and for all of us," said Jim Green, director of NASA's Planetary Science Division. "This is not, however, the detection or discovery of a new planet. It's too early to say with certainty there's a so-called Planet X. What we're seeing is an early prediction based on modeling from limited observations. It's the start of a process that could lead to an exciting result."
What is bullshit, and what has been fabricated by fraudsters and crazies, is that it will collide with Earth, [or pass close by] next year.
The following is an example of that bullshit......
http://planetxnews.com/2016/06/16/overwhelming-evidence-2017-arrival-planet-x-nibiru/
"There is no hiding this incoming solar system any longer! It consists of a dark star, smaller than our sun, which hosts seven orbiting bodies, some smaller than our moon and a couple of them larger than our Earth. The dark star is called “Nemesis” or “Planet X.” The blue planet is called the “Blue Kachina.” The planet that is larger than Earth that is orbiting the dark star is called “Nibiru.” It is also known as “The Planet of the Crossing” and the “Destroyer.” There is another object – some refer to it as “Helion.”
This system is, of course, not aligned with our solar system’s ecliptic, but is coming to us from an oblique angle and toward our South Pole. This makes observations difficult, unless you’re flying at a high altitude over South America with an excellent camera. As it intertwines and approaches it, will come from our south and loop all the way to the extreme north, then come back south again as it exits our orbital path.
The evidence to support this is overwhelming. There are 40 volcanoes erupting at the same time on Earth now. Earthquakes have dramatically increased both in number and intensity. The Elite are frantically building underground “safety” bunkers. The public is being kept in the dark deliberately to avoid panic. Storm systems are multiplying both in type, intensity and size. Sinkholes and cracks are appearing in the earth’s crust. Heatwaves are getting stronger and are lasting longer. I’m just waiting for the fat lady to sing!"
