Planet Nine: Research suggests our solar system has a hidden world

The strange orbit of 2015 BP519 strengthens the case for a ninth planet

A new paper reinforces the theory that a ninth planet exists in the outer solar system, beyond the orbit of Neptune. We’re not talking about Pluto, which was downgraded to a dwarf planet in 2006, but an object that could have 10 times the mass of Earth.

The possibility for this mysterious planet hinges on the movements of other objects further than Neptune. Published on the arXiv preprint server, a new paper using data from the Dark Energy Survey claims to have found an “extreme Trans-Neptunian Object” with a massive, tilted orbit around the Sun. The shape of this orbit implies an interaction with an unknown planet, the researchers claim.

In the Solar System, pretty much all objects orbit the Sun on the same plane. This new object, dubbed 2015 BP519, instead travels on an elliptical orbit that spans 35 to 862 times the radius of the Earth’s orbit, at a 54-degree angle to the plane taken by our planet. The team, led by University of Michigan graduate student Juliette Becker, modeled the object’s movement and decided they needed something to explain this strange orbit.

As Quanta Magazine reports, the study backs up a prediction made by Konstantin Batygin and Michael Brown, who argued in 2016 that the peculiar, looping orbits of worlds in the Kuiper belt is caused by a ninth planet dragging them along with its gravity. The movement of 2015 BP519 fits perfectly into this model, so while it isn’t complete proof of planet nine, it adds a crucial piece of evidence for a planet-sized entity, whose gravity is shepherding its neighbours in the outer Solar System.

Not everyone is convinced with this theory, with some experts suggesting that there could be a gamut of reasons for objects like 2015 BP519 to be nudged into puzzling orbits, given how little we know about the early Solar System. If you’re looking for something to fill the gap left by Pluto, however, this study is the strongest indication yet that there may be a ninth planet orbiting very, very far away.

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