"Another hiccup for Mayan doomsday believers: Although many scholars agree that Dec. 21 is the proper date on our calendar matching the end of the 13th b'ak'tun, there is some uncertainty over this, because some Mayan calendar units may have clicked over at sunset and others at sunrise. Some researchers have suggested that Dec. 23 or 24 may be a more accurate fit, Witschey said. Either way, however, the Maya would not have been running for their doomsday bunkers."