Scientists say they have found evidence of an unknown planet in our solar system

New findings represent the ‘strongest statistical evidence yet’ that Planet 9 exists, researcher says

Scientists say they have found new evidence that there is a hidden planet in our solar system.

For years, some astronomers have been suggesting that unusual behaviour on the edge of our solar system is best explained by another, undiscovered planet. That helps explain the orbits of objects that lie at the very far reaches of our solar system, more than 250 times away from the Sun than we are.

Now Konstantin Batygin, an astronomer who helped popularise the theory, says that he and his team have found yet more evidence that suggests that planet exists. The new work represents “the strongest statistical evidence yet that Planet 9 is really out there”, he said.

In the new work, scientists looked at a set of trans-Neptunian objects, or TNOs, which is the technical term for those objects that sit out at the edge of the solar system, beyond Neptune

The new work looked at those objects that have their movement made unstable because they interact with the orbit of Neptune. That instability meant they were harder to understand, so typically astronomers looking at a possible Planet Nine have avoided using them in their analysis.

Researchers instead looked towards those objects, and tried to understand their movements. And, Dr Batygin claimed, the best explanation is that they result from another, undiscovered planet.

The team carried out a host of simulations to understand how those objects’ orbits were affected by a variety of things, including the giant planets around them such as Neptune, the “Galactic tide” that comes from the Milky Way, and passing stars.

The best explanation was from the model that included Planet Nine, however, Dr Batygin said. They noted that there were other explanations for the behaviour of those objects – including the suggestion that other planets once influenced their orbit, but have since been removed – but claim that the theory of Planet Nine remains the best explanation.

Better understanding of the existence or not of Planet Nine will come when the Vera C Rubin Observatory is turned on, they note. That is currently being built in Chile, and when it is turned on it will be able to scan the sky to understand the behaviour of those distant objects.

“This upcoming phase of exploration promises to provide critical insights into the mysteries of our solar system’s outer reaches,” the team writes in their paper.

A paper describing the work, ‘Generation of Low-Inclination, Neptune-Crossing TNOs by Planet Nine’, is available now on arXiv.