The Nibiru collision 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 possibly 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 proposed 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 predicted collision 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 ancient astronaut writerZecharia Sitchin and his interpretations of Babylonian and Sumerian mythology, Sitchin himself denied any connection between his work and various claims of a coming apocalypse.
Astronomers point out that such an object so close to Earth would be easily visible to the naked eye (Jupiter and Saturn are both visible to the naked eye, and are dimmer than Nibiru would be at their distances), and would be creating noticeable effects in the orbits of the outer planets. Some counter this by claiming that the object has been hiding behind the Sun for several years, though such a claim is geometrically impossible. Images of Nibiru near the Sun taken by amateurs are usually the result of lens flares, false images of the Sun created by reflections within the lens.
Mike Brown notes that if this object's orbit were as described, it would only have lasted in the Solar System for a million years or so before Jupiter expelled it, and that there is no way another object's magnetic field could have such an effect on Earth.Lieder's assertions that the approach of Nibiru would cause the Earth's rotation to stop or its axis to shift violate the laws of physics. In his rebuttal of Immanuel Velikovsky's Worlds in Collision, which made the same claim that the Earth's rotation could be stopped and then restarted, Carl Sagan noted that, "the energy required to brake the Earth is not enough to melt it, although it would result in a noticeable increase in temperature: the oceans would [be] raised to the boiling point of water . . . [Also,] how does the Earth get started up again, rotating at approximately the same rate of spin? The Earth cannot do it by itself, because of the law of the conservation of angular momentum."
In a 2009 interview with the Discovery Channel, Mike Brown noted that, while it is not impossible that the Sun has a distant planetary companion, such an object would have to be lying very far from the observed regions of the Solar System to have no gravitational effect on the other planets. A Mars-sized object could lie undetected at 300 AU (10 times the distance of Neptune); a Jupiter-sized object at 30,000 AU (1000 times the distance of Neptune). To travel 1000 AU (30 times the distance of Neptune) in 2 years, an object would need to be moving at 2400 km/s, or faster than the galactic escape velocity. At that speed, any object would be shot out of the Solar System, and then out of theMilky Way galaxy into intergalactic space.