Lots of us grew up learning that there were nine planets in the Solar System. In the early 2000s we were told a different story, that Pluto was too small to be considered a full-fledged planet, and that it was more appropriate to categorize it as a “dwarf planet.” We grudgingly accepted that decision since we really didn’t have a choice, but now scientists are declaring that there might actually be nine planets in our little system, and the mysterious planet nine is one that we’ve never actually seen before.

“Hey, wait a second,” you’re probably thinking. “If there’s a ninth planet that we can’t see, how do we know it’s there?” Well I’m glad you asked, dear reader, because that’s exactly what a group of astronomers just published a new research paper about.

The work, which was co-authored by David Gerdes and Juliette Becker of the University of Michigan, focuses on the movements of newly-discovered object in the distant reaches of our Solar System. The object, which the scientists believe may be as large as a dwarf planet itself, is moving in a very peculiar way. In fact, it’s moving in a manner that suggests it’s being influenced by a much larger object. That much larger object is possibly Planet Nine.

“It’s not proof that Planet Nine exists,” Gerdes explains. “But I would say the presence of an object like this in our solar system bolsters the case for Planet Nine.”

The reason the researchers are confident that the object’s movements are being influenced by a larger body is that its orbit doesn’t match the vast majority of the large bodies in our system. Instead, its orbit it tilted at a 54 degree axis to the established Solar System plane. One very suitable explanation is that it was pulled into this odd orbit by a planet roughly ten times the mass of Earth.

This isn’t the first time that astronomers have spotted odd behavior in distant objects, and it’s also not the first time they’ve used that data in support of the Planet Nine theory. However, some Planet Nine skeptics in the scientific community urge caution in jumping to conclusions. Mankind’s understand of the development of the Solar System still has plenty of holes, and just because something we see today as bizarre can’t be fully explained — like the odd orbit of a distant dwarf planet — it doesn’t necessarily mean that Planet Nine was the culprit.

The search for Planet Nine has shown no signs of slowing down, and until its existence can either be proven or disproven we’ll likely see more evidence piling up on both sides of the argument.