2012 phenomenon galaxy, or Earth's collision with a mythical planet called Nibiru. Scholars from various disciplines quickly dismissed predictions of concomitant cataclysmic events as they arose. Professional Mayanist scholars stated that no extant classic Maya accounts forecast impending doom, and that the idea that the Long Count calendar ends in 2012 misrepresented Maya history and culture, while astronomers rejected the various proposed doomsday scenarios as pseudoscience, easily refuted by elementary astronomical observations. December 2012 marked the conclusion of a "b'ak'tun"—a time period in the Mesoamerican Long Count calendar, used in Central America prior to the arrival of Europeans. Although the Long Count
Mesoamerican calendars menstrual period and birth, unlike Naegele's rule which is 40 weeks (280 days) between the "last" menstrual period and birth. It is postulated that midwives originally developed the calendar to predict babies' expected birth dates. A third theory comes from understanding of astronomy, geography and paleontology. The mesoamerican calendar probably originated with the Olmecs, and a settlement existed at Izapa, in southeast Chiapas Mexico, before 1200 BCE. There, at a latitude of about 15° N, the Sun passes through zenith twice a year, and there are 260 days between zenithal passages, and gnomons (used generally for observing the path of