The Nibiru cataclysm is a supposed disastrous encounter between the Earth and a large planetary object (either a collision or a near-miss) which certain groups believe will take place in the early 21st century. Believers in this doomsday event usually refer to this object as Planet X or Nibiru. The idea that a planet-sized object could collide with or pass by Earth in the near future is not supported by any scientific evidence and has been rejected as pseudoscience by astronomers and planetary scientists.
The idea was first put forward in 1995 by Nancy Lieder, founder of the website ZetaTalk. Lieder describes herself as a contactee with the ability to receive messages from extra-terrestrials from the Zeta Reticuli star system through an implant in her brain. She states that she was chosen to warn mankind that the object would sweep through the inner Solar System in May 2003 (though that date was later abandoned) causing Earth to undergo a pole shift that would destroy most of humanity. The prediction has subsequently spread beyond Lieder’s website and has been embraced by numerous Internet doomsday groups, most of which link the event to the 2012 phenomenon. Although the name “Nibiru” is derived from the works of the late ancient astronaut writer Zecharia Sitchin and his interpretations of Babylonian and Sumerian mythology, Sitchin denied any connection between his work and various claims of a coming apocalypse.