Slowly we're getting closer to proving another planet is out there. I do like it when nutters spewing out 100's of mad theories a month get one correct, in this case its the existence of Nibiru.
Maybe i'm way off here, the government mind control satellites seem to have got to my reviewers.
I think the planet X moniker originally meant 'x' as unknown (it was coined during the search that found Pluto). Nowadays, it has been used to refer to several distinct theories including Planet IX. I dunno when exactly the X got re-interpreted.
What I do know is WE'RE DOOOOMED! (according to the internet).