2012 and the New Age
The New Age interpretation of the alleged Mayan prophecy of 2012 is often called the “Planet X Hypothesis,” which is believed to be the name of an undiscovered planet that is spiraling toward Earth. Some in the New Age community believe this plant will hit Earth on December 21, 2012 resulting in chaos and death; others believe it will merely pass by Earth on that date, the consequence of which will cause humanity to go through favorable physical and spiritual transformations.
It is suggested by some in the New Age community that the Sumerians discovered a planet called Nibiru, others call it “Planet X,” that is hurdling toward Earth. According to New Age teacher Nancy Lieder, Nibiru was supposed to hit the earth in May of 2003. However, when the forecast failed, she revised the date to 2010, and later, the date was changed to December 21, 2012.
According to this view, Nibiru would cause a pole shift to occur on Earth, which, hypothetically speaking, is when the North and/or South Pole changes locations, catastrophically altering the Earth’s weather and oceans. This theory is key to the plot of the movie 2012 starring John Cusack and Amanda Peet.
ZetaTalkLieder is the founder of a group called ZetaTalk. She claims to be a “contactee” who can receive special messages from aliens through a device they implanted in her brain. Lieder reports that the aliens call the “Zeta Reticilu Star System” home, a location made popular when husband and wife Betty and Barney Hill claimed to have been abducted by extraterrestrials from there in 1961.
In 1997, Lieder, speaking for the Zeta's, said the Hale-Bopp comet didn’t exist. She said the comet was actually a distant star that the government was using to distract people from the arrival of Nibiru. When Hale-Bopp arrived in earth’s sky, it was one of the brightest and longest-observed comets in the last hundred years.
The history of Nibiru is questionable. The most reliable history suggests the Sumerian people used the word “Nebiru” or “Nibirum” (there is a slight spelling difference in the ancient script), to describe the high point of the summer solstice, which would therefore associate it with a constellation, not a roving planet headed toward Earth.
Phil Plait. "Planet X Page" found at http://www.badastronomy.com/bad/misc/planets