Are there really 8 planets in the solar system?

So we are all familiar with the 8 planets. Mercury, Venus, Earth, Mars, Jupiter, Saturn, and Neptune. But is that where it ends? Of course other solar systems house trillions of other planets, and billions more are predicted to be wandering our galaxy alone. But what about much closer to home? Even within our own solar system. Well, some people believe that a massive object has been lurking 1,000 times as far from the Sun as the Earth. Scientists have noticed disturbances in the orbit of objects in the Kuiper Belt. Similar to the Asteroid belt but much farther away from the Sun, the belt houses millions of (mostly) small objects such as comets. Or so we thought. There is a rising amount of evidence that points to something much more massive there. Something between 10 and 20 times as massive as our home planet. Planet 9. 

If this planet exists, it could redefine our understanding of our solar system, and raise many questions. Did it from like the other planets in the solar system? Was it captured from the outside "world?" Did it come from another star? How have we not noticed it all this time? Either way it goes, it will be something for the record books.