No. 25: Jan-Feb 1983
Something big out there beyond Neptune perturbs the orbits of the sun's outer fringe of planets. In addition, there are unexplained perturbations in the orbits of earth satellites, peculiar periodicities in the sunspot cycle, and equally puzzling regularities in earthquake frequency. Infrared detectors have also picked up unidentified objects in the sky. These anomalies might all be explained by the existence of a large, dark planet with several moons -- or, if the mystery object turns out to be very far away, by a very large, dark stellar companion of our sun with its own system of planets.
Several astronomers have been trying to pin down the properties of this Planet X or Massive Solar Companion (MSC). John P. Bagby has recently published a novel solution to this nagging puzzle in celestial mechanics. He suggests that the Massive Solar Companion is actually a distributed system; that is, appreciable mass also occupies the several stable Lagrangian points. The total MSC mass might be as much as half the sun's mass, perhaps 100 Astronomical Units (100 times the earth's distance from the sun.) If the MSC and its attendants are this massive, astronomers will have to revise the mass and density of the sun downward by a good bit. (What they have done in the past is estimate the mass of the solar system as a whole and assumed it mostly resides in the sun.) This would require a large change in our model of the sun and its system of planets.
(Bagby, John P.; "Evidence for a Tenth Planet or Massive Stellar Companion Beyond Uranus," paper given at the Tomorrow Starts Here Conference, September 1982.)
Reference. Our Catalog: The Sun and Solar System Debris contains an entire section on Planet X. Ordering information at: here.