There’s a controversy in planetary science — some researchers propose that the Solar System has a ninth planet with a distant orbit around the Sun.
In search of a ninth planet has been on astronomers minds for some time. They suggest that there is a planet nine since some strange orbits have been found in our solar system. Researchers believe that some gravitational pulls from some Neptunian objects may be causing these orbits. They found that perhaps the objects in orbit are 10 times more massive that Earth and are about 600 astronomical units (about 93 million miles) away from the Sun. Other solar systems are known to have many objects in their outer reaches and if we don’t see one in ours doesn’t mean that it doesn’t exist.
When you observe from the inside of the system you may not see the whole thing.
The talk of Planet Nine first emerged in January 2015 when two astronomers from the California Institute for Technology (Caltech) suggested that a Neptune-sized planet orbits our Sun in a highly elongated orbit that lies far beyond Pluto.
Their claim was based on mathematical modeling and computer simulations and not actual observation. The astronomers suggest that a ninth planet is responsible for the gravitational effect on a group of icy objects that lie beyond the orbit of Neptune in the Kuiper Belt. Those small objects have elongated orbits with similar characteristics, as if caused by one massive object.
Although its existence has not been proven yet, this could be the first discovery of a new planet orbiting the Solar System in two centuries.