JudasIscariot: My GF drives me crazy when she starts talking about this shadow planet that supposedly hides from our telescopes and it's supposed to be on the same orbit as Earth and that the inhabitants are evil and they feed on our collective negative emotions....
What ze FAK?
It's counter-Earth! It was a legitimate theory based on actual science, until it was proven conclusively wrong. The idea was that another planet is in the same orbit as Earth, but is at the Lagrange point opposite the sun, so we can never actually see it from Earth. We now know there is really nothing there.
Oooh, unless she means Nemesis, which is a bunch of complete bullshit but is still pretty cool. Nemesis is supposed to be a Brown Dwarf star that orbits our sun in an eccentric orbit that keeps outside the Oort Cloud most of the time, but every 26 million years or so, it makes a pass by us, causing an extinction event.