I know about the Mayan calendar being the end of the world, or the end of this age, but how do aliens come into this? I fail to see the jump to aliens. Could someone please enlighten me?

They have mistakenly stated that Nibiru/Planet X is showing up around that time. The problem is the writer of those books Mr Sitchin states that Nibiru last showed up @ 600BC and is not due to arrive in another 3600 years meaning Nibiru will not show up until 3000AD. The aliens are the inhabitants of Nibiru who created us humans (the Annunaki) if you are to believe Mr Sitchin's theories

[edit on 7/2/2008 by kidflash2008]

Yes I think they have taken the story of nibiru and associated it with the myan calendar.There really isn't anything close enough to earth to just appear and get here by 2012 now anyway.
Unless something happened say in the kuiper belt and something was launched in this direction which I did read something about.Something about Neptune being able to launch objects that try to collide with it.That was actually a real scientific possibility however I believe they said it was extremely unlikely.
Many of those people just like to sell books and associated products.