In a wonderfully punchy, and technically brilliant paper the scientists Konstantin Batygin and Mike Brown of Caltech have set the world abuzz with their claim of a giant planet lurking well beyond Pluto and its Kuiper-belt kin.
In brief, the oddly clustered orbital configurations of a bunch of distant Kuiper-belt bodies might be best explained by the gravitational perturbations of a planet of at least 10 Earth masses, orbiting with a semi-major axis of some 700 astronomical units (AU), and an ellipticity of 0.6 (which would bring it as close to the Sun as about 280 AU at perihelion, during a roughly 19,000 year orbit).
It's pretty heady stuff, and although proposals have been made before for such a planet, this new analysis is perhaps the most compelling yet.
But chucking a new giant planet in our solar system's fringes raises all sorts of questions, so let me try to address some of those here.
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