Planet nine
An artist's concept of the possible ninth planet, dubbed Planet Nine, which is believed to exist because of the pull it exerts on the outer objects in our solar system. Caltech/R. Hurt (IPAC)

For years, theories of a ninth planet sitting beyond the orbit of Pluto have been doing the rounds. Astronomers across the globe have been searching for this planet with little to no success. However, just recently, a group of researchers discovered a piece of evidence indicating the ghostly world could be hiding in the farther reaches of our solar neighborhood.

The evidence, as a report from Quanta Magazine points out, is a space-rock with a weird orbital nature.

Nearly all space objects lie on the same plane of the solar system and can be seen from different telescopes and observatories. However, the newly discovered object, called 2015 BP519, was spotted in a region above the plane, something the researchers did not expect to see in the data collected for the Dark Energy Survey, which aims to assess dynamics of the expansion of the universe.

According to the researchers, the object ended up in that region due to its elliptical orbit around sun. 2015 BP519’s orbit is 54 percent titled with respect to the plane of the Solar System. Though not many details about the object or its journey are available, the group, which modeled its movement, posits the radius of its orbit could fall anywhere between the 35 to 862 times the radius of Earth’s orbit around sun.

The group, led by University of Michigan graduate student Juliette Becker, observed the object, tracked its movement, and ran simulations to understand its origin story. However, nothing could explain how it got its weird orbit. They needed a source that might have influenced its journey in the long term, which is exactly where the theory of the ninth planet comes in.

As per the group, the hypothesized Planet Nine, which could be 10 times the mass of Earth and 20 times farther from the sun than Neptune, explains the strange orbital path of this object. Their simulations made complete sense on including the ninth planet and suggested the strong pull of ghostly world might have dragged the object away from the plane of the Solar System.

That said, the discovery bolsters the Planet Nine theory but cannot be considered as a firm evidence of another planet hiding in our stellar neighborhood.

“It’s not proof that Planet Nine exists,” co-author of the study David Gerdes told Quanta Magazine. “But I would say the presence of an object like this in our solar system bolsters the case for Planet Nine.”

It is also worth noting astronomers are dubious about the new theory, mainly because the history of our solar system and the first planets have only been a mystery. As the report noted, there are many possibilities for this case, such as the push from dwarf planets or stars among which the sun was born.

The arXiv preprint of the paper titled “Discovery and dynamical analysis of an extreme trans-Neptunian object with a high orbital inclination,” is available online.