The 2012 phenomenon comprises a range of apocalyptic beliefs that cataclysmic or transformative events will occur on December 21, 2012, which is said to be the end-date of a 5,125-year-long cycle in the Mayan Long Count calendar. Various astronomical alignments and numerological formulae related to this date have been proposed, but none have been accepted by mainstream scholarship.
A New Age interpretation of this transition posits that during this time, Earth and its inhabitants may undergo a positive physical or spiritual transformation, and that 2012 may mark the beginning of a new era. Others suggest that the 2012 date marks the end of the world or a similar catastrophe. Scenarios posited for the end of the world include the Earth's collision with a passing planet (often referred to as "Nibiru") or black hole, or the arrival of the next solar maximum.
Scholars from various disciplines have dismissed the idea that a catastrophe will happen in 2012, stating that predictions of impending doom are found neither in classic Maya accounts nor in astronomy. Mainstream Mayanist scholars state that the idea that the Long Count calendar "ends" in 2012 misrepresents Maya history. The modern Maya, on the whole, have not attached much significance to the date, and the classical sources on the subject are scarce and contradictory, suggesting that there was little if any universal agreement among them about what, if anything, the date might mean.
Astronomers and other scientists have rejected the apocalyptic forecasts, on the grounds that the anticipated events are precluded by astronomical observations, or are unsubstantiated by the predictions that have been generated from these findings. NASA has compared fears about 2012 to those about the Y2K bug in the late 1990s, suggesting that an adequate analysis should preclude fears of disaster.