Dwarf planet's weird orbit convincing evidence of a ninth, hidden planet

The evidence of a dark, mysterious ninth planet deep in space beyond the orbit of Neptune is mounting. Photo / Nasa

It may not be Nibiru. But the evidence that there's a mysterious wandering planet on the outskirts of our solar system just keeps growing.

One planet is a rich source of doomsday prophecy speculation. The other a tantalising target for our planet's astronomers.

Nibiru is an incorporeal world that has supposed to have hit us any number of times. There is no evidence it exists.

But Planet Nine (or Planet X, depending on whom you speak to) is looking very real.

We know it is out there, in the dark outer-reaches of our Solar System, because of the gravitational influence it has on other distant bodies.

It remains elusive.

But another big clue has further narrowed down where it might be.

A team of astronomers have found a wayward dwarf planet, dubbed 2015 BP519.

It's odd.

It's a long way out — some 55 times further from the Sun than our Earth.

It's orbit is extreme. It's inclined some 54 degrees off the plane of the rest of the planets, and will eventually take it some 450 times further out than our Earth.

But the gravity of Neptune really should be enough to have kept it in line with the rest of the Solar System.

The wayward paths of numerous distant asteroids and dwarf planets beyond the orbit of Neptune strongly suggest there is a big, planet-size word circling near the Kuiper Belt. Photo / Supplied

The dwarf planet's bizarre behaviour can only really be explained by that there's something big out there. Really big. And it's bullying smaller objects such as 2015 BP519 about.

"(We) find that 2015 BP519 adds to the circumstantial evidence for the existence of this proposed new member of the solar system," the paper, which has been submitted to The Astronomical Journal , reads.

The dwarf planet is just another wanderer beyond the orbit of Neptune that hints to the existence of Planet Nine.

In 2014, it was noticed that the dwarf planet Sedna, object 2012 VP113 and other leftover pieces of rubble were following somewhat unnatural paths. This led to the idea that there may be a planet-sized 'shepherded' out there somewhere.

By 2016, more wayward objects were seen somewhat out of place. Astronomers Mike Brown and Konstantin Batygin gave the ghostly planet a name — Planet Nine — and offered an estimate of its characteristics.

It could be about 10 times the weight of Earth. It is roughly 600 times further out from the Sun than the Earth. It takes roughly 20,000 years to complete each orbit.

"If you were to remove this explanation and imagine Planet Nine does not exist, then you generate more problems than you solve," Batygin said. "All of a sudden, you have five different puzzles, and you must come up with five different theories to explain them."

Since then, a multitude more Trans-Neptune Objects (TNOs) have been found where they don't belong, following orbits that shouldn't exist.

" (2015 BP519) is not proof that Planet Nine exists," researcher David Gerdes told Quanta. "But I would say the presence of an object like this in our solar system bolsters the case for Planet Nine."

Co-astronomer Batygin took the argument further: "There is no other reasonable way to populate the Kuiper Belt with such highly inclined bodies. I think the case for the existence of Planet Nine is now genuinely excellent."