A large yellow star with four planets.  The third planet follows
a highly irregular orbit that is theoretically impossible but
shows no degeneration over time. Recently visited by the U.S.S.
Enterprise NCC-1701-D, the system as displayed in a holographic
motion model puzzles Captain Picard enough to try to work out
the physics involved. The erratic orbit may have been the cause
of some system-wide disaster or other unexplained phenomenon;
Captain Picard says an answer to the orbit's stability "may
explain what happened in that system."