An accurate, but absurd assessment demonstrating how well we understand the solar system despite the fact that there may be a few new discoveries to be made about it.
From xkcd (Randall Munroe).
UPDATE January 25, 2016 (based upon input from the comments):
Objects much larger than the top right corner in the box ("Planets Ruled Out Because We Could See Them During the Day") are ruled out because they would be stars. The size of the solar system (before objects would fall into another star's orbit) is about 107,000 AU which means that the boundary on the right hand side of the chart actually extends beyond the size of the solar system by a bit. Objects smaller than dwarf planets don't have sufficient gravitational pull to be even roughly spherical due to gravitational forces. Very large planets have been ruled out by the LISE survey everywhere in the solar system.
The hypothetical Planet Nine has correctly been placed about 700 AU out and at a mass which would assume a Neptune or Uranus diameter and would be somewhat smaller if it was rocky instead.