A mysterious object once thought to be an undiscovered planet on the edge of our solar system could be a tiny black hole, a study claims.

Experts have argued for years that a distant ninth world in our solar system, known as Planet Nine, orbits the sun in a region well beyond Neptune.

The idea was put forward in 2016 by astronomers to explain the wobbly orbits of distant objects.

According to them, the hypothetical world, also known as Planet X, could have a mass about 10 times that of Earth and take up to 20,000 years to orbit the sun.

However, a new study suggests Planet Nine isn’t a planet at all.

Instead, a team of scientists led by Durham University claim it’s a black hole.

If they’re correct, they say, they’ll be able to find evidence in the form of flashes of radiation ejected from the object.

Specifically, gamma rays should be created by interactions between a mysterious substance called dark matter surrounding the black hole.

Based on previous predictions of Planet Nine’s mass, the black hole would be so dense, it could only be the size of a bowling ball.

As it’s so small, it’s unlikely the black hole poses any threat to Earth — for now.

The team plans to find crucial evidence to back the wacky theory.

The research was published in the pre-print journal Arxiv.

The hypothetical Planet Nine has never been observed by scientists, and it’s still unclear if it actually exists.

Astronomers at the California Institute of Technology put forward the idea to explain the wobbly orbits of distant objects.

The space bodies in question lie in the Kuiper Belt, a region beyond Neptune filled with dwarf planets and icy debris.

Scientists think the gravitational pull of an as-yet-undiscovered ninth planet in the solar system could be yanking the objects into strange orbits.

Planet Nine is also wrapped up in a strange conspiracy theory.

Conspiracy nuts have claimed for years that a rogue planet called Nibiru may one day smash into Earth, destroying all life as we know it.

Some say Nibiru is, in fact, Planet Nine. They reckon its oval orbit will someday take it into the path of our planet.