Astronomers have noticed that some distant objects far beyond Pluto are behaving oddly and are speculating as to whether there may be a huge ninth planet ten times larger than earth at the edge of our solar system. Nicknamed Planet Nine, the structure has an extremely elongated orbit that takes from 10,000 to 20,000 years to swing once around the sun.

The icy planet evaded detection because it is so far away, but scientists at the California Institute of Technology (Caltech) noticed it while trying to understand why the orbits of a handful of space rocks aligned for no apparent reason.

“We saw a strange signal in the data that meant something odd was going on in the outer solar system,” says Caltech astronomer Mike Brown. After none of the “mundane explanations” worked out, the astronomers began to theorize on the possibility of another planet.

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Zooming out from the orbit of Neptune, we see the six aligned objects, and how they fall within the same plane

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Planet Nine is required to be anti-aligned to these objects, but shares the same plane.

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The presence of Planet Nine also forces objects into orbits that are perpendicular to the plane of the solar system and oriented at right angles to Planet Nine.