The Nibiru cataclysm is a supposed disastrous encounter between Earth and a large planetary object (either a collision or a near-miss) that certain groups believed would take place in the early 21st century. Believers in this doomsday event usually refer to this object as Nibiru or Planet X. The idea was first put forward in 1995 by Nancy Lieder, founder of the website ZetaTalk. Lieder claims she is a contactee with the ability to receive messages from extraterrestrials 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 postponed) causing Earth to undergo a physical 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. In the late 2000s, it became closely associated with the 2012 phenomenon. Since 2012, the Nibiru cataclysm has frequently reappeared in the popular media, usually linked to newsmaking astronomical objects such as Comet ISON or Planet Nine. Although the name "Nibiru" is derived from the works of the "ancient astronaut" writer Zecharia Sitchin and his interpretations of Babylonian and Sumerian mythology, he denied any connection between his work and various claims of a coming apocalypse. A prediction by self-described "Christian numerologist" David Meade that the Nibiru cataclysm would occur on 23 September 2017 received extensive media coverage.
The idea that a planet-sized object will collide with or closely pass by Earth in the near future is not supported by any scientific evidence and has been rejected by astronomers and planetary scientists as pseudoscience and an Internet hoax. Such an object would have destabilised the orbits of the planets to the extent that their effects would be easily observable today. Astronomers have hypothesized many planets beyond Neptune, and though many have been disproved, there are some that remain viable candidates such as Planet Nine. All the current candidates are in orbits that keep them well beyond Neptune throughout their orbit, even when they are closest to the Sun.
History
Nancy Lieder and ZetaTalk
The idea of the Nibiru encounter originated with Nancy Lieder, a Wisconsin woman who claims that as a girl she was contacted by gray extraterrestrials called Zetans, who implanted a communications device in her brain. In 1995, she founded the website ZetaTalk to disseminate her ideas. Lieder first came to public attention on Internet newsgroups during the build-up to Comet Hale–Bopp's 1997 perihelion. She stated, claiming to speak as the Zetans, that: "The Hale–Bopp comet does not exist. It is a fraud, perpetrated by those who would have the teeming masses quiescent until it is too late. Hale–Bopp is nothing more than a distant star, and will draw no closer." She claimed that the Hale–Bopp story was manufactured to distract people from the imminent arrival of a large planetary object, "Planet X", which would soon pass by Earth and destroy civilization. After Hale–Bopp's perihelion revealed it as one of the brightest and longest-observed comets of the last century, Lieder removed the first two sentences of her initial statement from her site, though they can still be found in Google's archives. Her claims eventually made the New York Times.
Lieder described Planet X as roughly four times the size of Earth, and said that its closest approach would occur on May 27, 2003, resulting in Earth's rotation ceasing for exactly 5.9 terrestrial days. This would be followed by Earth's pole destabilising in a pole shift caused by magnetic attraction between Earth's core and the magnetism of the passing planet. This in turn would disrupt Earth's magnetic core and lead to subsequent displacement of Earth's crust. After the 2003 date passed without incident, Lieder said that it was merely a "white lie ... to fool the establishment". She refused to disclose the true date, saying that to do so would give those in power enough time to declare martial law and trap people in cities during the shift, leading to their deaths.