Two american scientistshas calculated that a large Jupiter mass planet may be hiding in the gap between Pluto and the inner Oort cloud of comets

They present updated dynamical and statistical analyses of outer Oort cloud cometary evidence, suggesting that the Sun has a wide-binary jovian mass companion. Their results support a conjecture that there exists a companion of mass of 1-4x Jupiter masses, orbiting in the innermost region of the outer Oort cloud.

The most restrictive prediction is that the orientation angles of the orbit plane in galactic coordinates are centered on X, the galactic longitude of the ascending node = 319^o and i, the galactic inclination = 103^o (or the opposite direction) with an uncertainty in the orbit normal direction subtending <2% of the sky.

Such a companion could also have produced the detached Kuiper Belt object Sedna. If the object exists, the absence of similar evidence in the inner Oort cloud implies that common beliefs about the origin of observed inner Oort cloud comets must be reconsidered.

Evidence of such a large planet would have been recorded by the Wide-field Infrared Survey Explorer (WISE) which has completed its primary mission and is continuing on secondary objectives.

Source: University of Louisiana