December 21'st, 2012: Are you Worried?

December 21 — The Mesoamerican Long Count calendar, notably used by the Maya civilization among others of pre-Columbian Mesoamerica, completes its thirteenth b'ak'tun cycle since the calendar's mythical starting point (equivalent to 3114 BC August 11 in the proleptic Gregorian calendar, according to the "GMT-correlation" JDN= 584283). The Long Count b'ak'tun date of this starting point (13.0.0.0.0) is repeated, for the first time in a span of approximately 5,125 solar years. The significance of this period-ending to the pre-Columbian Maya themselves is unclear, and there is an incomplete inscription (Tortuguero Monument 6) that records this date. It is also to be found carved on the walls of the Temple of Inscriptions in Palenque, where it functions as a base date from which other dates are computed. However, it is conjectured that this may represent in the Maya belief system a transition from the current Creation world into the next.[citation needed]

December 23 — The alternative date for the completion of the thirteenth b'ak'tun cycle in the Maya calendar, using a version of the GMT-correlation based on a JDN of 584285 (a.k.a. the "astronomical" or "Lounsbury correlation"), which is supported by a smaller number of Mayanist researchers.