many therioes abound as to IF there is another Planet attached to our Solor System ,some are because of superstition others because of planetary orbit descrepencies & some say the math is there to indicate more mass is involved in system makeup. most likey there are other planetoids further out than pluto , but nothing indicates a massive dark planet that would cause planetary orbital drag or that it swings thru the inner solor system even IF on a 100,000 year orbit we would still see its affects on system for millions of years( takes that long for planet orbits to realign)