Astronomers Think Planet Nine Threw Our Solar System off Tilt

Two groups of scientists reach the same conclusion about the elusive ninth planet.

Somewhere beyond Pluto and the Kuiper Belt, in the farthest reaches of our solar system, a ninth planet is thought to circle the sun.

Planet Nine has never been spotted, but the gravitational pull of a massive planet would explain some strange behaviors of bodies in our solar system. For example, objects in the Kuiper Belt that orbit the sun perpendicular to the plane of the planets. Some researchers even believe the hypothesized planet is responsible for mass extinctions in the Earth’s history.

Now, there is evidence to suggest that Planet Nine caused our entire solar system to deviate from its original plane.

SEE ALSO: Planet Nine May Have Been “Kicked” to the Outer Solar System by Jupiter and Saturn

All the planets in our solar system — except Mercury — orbit the sun within two or three degrees of each other, however, the sun spins on a plane that is tilted by six degrees. This has led astronomers to believe that either the sun has spun sideways or the planets have been swayed from their original alignment.

In two scientific papers published on arxiv.org this week (July 14 and 18), two indepedent research teams have concluded that Planet Nine would explain this misalignment.

^{Diagram showing the different angles of orbit for Planet Nine, the inner planets, and the sun. Credit: Bailey et al./arxiv.org}

In their paper, researchers from Caltech led by Michael Brown describe the tilting of the planets as an “inescapable consequence of the existence of Planet Nine.” The planet is thought to be 10 times more massive than Earth, so over the lifetime of our solar system, it would have significantly influenced the orbits of the other planets.

Publishing their work 4 days later, a team of Brazilian physicists arrived at the same conclusion using different analytic methods. Additionally, their paper calculates restrictions on the size and orbit Planet Nine, based on how much it has perturbed the orbits of the planets.

Both research papers are awaiting peer-review.

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