An artist’s impression of Planet 9
For decades, scientists have theorised that there is a ninth planet – what would have been 10th were it not for the downgrade of Pluto to a dwarf planet – in our galactic neighbourhood.
The planet is believed to be 10 times bigger than Earth and 20 times farther out from the sun than Neptune – the outer-most planet in the solar system.
While Planet Nine’s existence has yet to be officially proven, esteemed researchers strongly suspect that there is a large planet lurking in the far edge of our solar system.
If the planet is there, then it could explain why the solar system is slightly off balance.
Is there a ninth planet in the solar system?
In most star systems, the surrounding planets tend to rotate in line with their host.
However, in ours, the planets are at an angle of six degrees off its axis.
Konstantin Batygin, a planetary astrophysicist at the California Institute of Technology (Caltech) in Pasadena, said: “Over long periods of time, Planet Nine will make the entire solar-system plane precess, or wobble, just like a top on a table.”
There are also a number of other odd features in our solar system that would be explained by Planet Nine.
The planet would be 10 times larger than Earth
Dr Batygin said: “There are now five different lines of observational evidence pointing to the existence of Planet Nine.
“If you were to remove this explanation and imagine Planet Nine does not exist, then you generate more problems than you solve.
“All of a sudden, you have five different puzzles, and you must come up with five different theories to explain them.”
One of the weird features is that the Kuiper Belt – a circumstellar disc full of icy asteroids, comets and dwarf planets which encompasses the solar system – orbits in the opposite direction to the planets within it.
The existence of Planet Nine would explain this anomaly, says Dr Batygin.
He explained: “No other model can explain the weirdness of these high-inclination orbits.
“It turns out that Planet Nine provides a natural avenue for their generation.
“These things have been twisted out of the solar system plane with help from Planet Nine and then scattered inward by Neptune.”