16:40 14 June 2016
In January, astronomers in California predicted the existence of a ninth planet in our solar system. Although it has yet to be observed, it has been predicted that it could be made up of iron and ice, similar to Neptune and Uranus.
Since the announcement, scientists have formed theories that range from how it might have been an exoplanet stolen by our sun to how it could have wiped out the dinosaurs.
Professor Andrew Coates, deputy director at the Mullard Space Science Laboratory UCL, provided information we need to understand the mysterious world.
The existence of the planet was suggested after scientists noticed that objects in its vicinity were moving strangely.
A recent study said that it might have started as a forming outer planet core from our own early solar system, which expelled to the edge of the solar system, possibly by a collision. However, the study added, that it could also be that the sun have stolen Planet Nine from a nearby star in the Milky Way 4.5 billion years ago.
At the moment, the lack of direct observations of Planet Nine and the whole range of objects, which may be affected by it mean that the explanations are poorly constrained.