The potential existence of an undiscovered planet in our own solar system has intrigued astronomers for years.
The undiscovered theoretical planet in the outer reaches of our solar system may actually be a black hole.
The important new find also hints at the presence of another, much larger planet in the outer solar system.
Scientists have come up with an alternative explanation for the peculiar orbits of some distant objects.
A small solar system object with a strange orbit has hinted at the presence of a large, unknown world.
Scientists have been looking to the past to help them determine the whereabouts of the elusive ninth planet.
Scientists have developed a computer simulation that defines the exact orbit and behavior of Planet Nine.
Astronomers have suggested that there may be more than one mystery planet in the outer solar system.
Astronomers from around the world have been combining their efforts to seek out the new planet.
A large planet lurking in the outer solar system could be causing the sun's rotational axis to tilt.
A new theory has suggested that the new planet could be responsible for periodic mass extinction events.
The case for a hidden gas giant in the outer solar system continues to go from strength to strength.
Astronomers in France have managed to narrow down the area in which the new planet could be located.