I take this stuff with a grain of salt, even if I don't know how true it is. There have been plenty of false doomsdays in the past though I can't say much since I havn't researched them, but I think people have probably misinturpreted something, I mean it was probably decided that there is a 99.9% chance that there might be another planet out there that might join are solar system.

The one reason that convinces me is you would hear this alot more in todays society if it were likely.