For years there was speculation that on December 21, 2012, the world as we know it would end. Some predicted that we’d be wiped out by a natural disaster like a giant tidal wave, an Earth-wide earthquake or a tremendous volcanic eruption. Others believed that on that day in December, the Earth would collide with a mysterious “Planet X,” causing magnetic pole shifts, gravitational reversals or a black hole so big that our solar system would simply disappear. What’s more, believers said that this news was not really news at all; on the contrary, they argued, we have known about the coming apocalypse since the ancient Maya predicted and recorded it on their Long Count calendar more than 2,200 years ago.

The Ancient Maya

Of course, there is no concrete evidence that the Maya–a diverse group of indigenous people who lived in parts of present-day Mexico, Belize, Guatemala, El Salvador and northwestern Honduras from about 2000 B.C.–could truly predict the future. They did, however, develop one of the most sophisticated and complex civilizations in the Western Hemisphere. They figured out how to grow corn, beans, squash and cassava in sometimes-inhospitable places; how to build elaborate cities without modern machinery; how to communicate with one another using one of the world’s first written languages; and how to measure time using not one but two complicated calendar systems.

Did you know? Historians have surmised that the Maya chose the Long Count calendar's base date to commemorate the mid-August 3114 BC passage of the sun over a particularly sacred site in southern Mexico.

The Calendar Round

The first Mayan calendar, known as the Calendar Round system, was based on two overlapping annual cycles: a 260-day sacred year and a 365-day secular year that named 18 months with 20 days each. (Five “unlucky” unnamed days were tacked on at year’s end.) Under this system, each day was assigned four pieces of identifying information: a day number and day name in the sacred calendar and a day number and month name in the secular calendar. Every 52 years counted as a single interval, or Calendar Round, and after each interval the calendar would reset itself like a clock.

The Long Count Calendar

But because the Calendar Round measured time in an endless loop, it was a bad way to fix events in an absolute chronology or in relationship to one another over a long period. For this job, a priest working in about 236 B.C. devised another system: a calendar that he called the Long Count. The Long Count system identified each day by counting forward from a fixed date in the distant past. (In the early 20th century, scholars found that this “base date” was August 11 or August 13, 3114 BC.) It grouped days into sets, or cycles, as follows:baktun (144,000 days), k’atun (7,200 days), tun (360 days), uinal or winal (20 days) and kin (one day). (So, for example, a date that was exactly 144,000 days from the calendar’s base date would be called, for 1 baktun, 0 k’atun, 0 tun, 0 uinal and 0 kin.)

The Long Count calendar worked the same way that the Calendar Round did–it cycled through one interval after another–but its interval, known as a “Grand Cycle,” was much longer. One Grand Cycle was equal to 13 baktuns, or about 5,139 solar years.

The End of the World?

The Maya who developed the Long Count calendar believed the end of one cycle would simply signal the beginning of another. According to this logic, a new Grand Cycle would start on December 22, 2012. However, some people in the U.S. and Europe came to believe that the calendar would not reset itself. Instead, they said, the end of the cycle would bring the end of the world. Some of these doomsayers claimed that there was a scientific explanation for their prediction: On December 21, they said, the winter solstice and the Milky Way’s equator would align. For their part, scientists pointed out that the coincidence of these two events would actually have no effect on the Earth–and furthermore, without 20th-century radio telescopes the Maya could not have known that the galactic equator even existed, much less where it would be in 2,000 years. Other prognosticators had more outlandish theories. Some believed that the Maya were following extraterrestrial instructions when they developed their calendar, for instance, while others fear that aliens would use the Long Count calendar to time their takeover of our planet. Either way, this vision of the future was an unpleasant one, combining Biblical plagues like fires and floods with more cinematic catastrophes like planetary collisions, extreme global warming and mass extinction, and explosions large and small.

Today, there are more than 6 million Maya in Mexico and Central America, and very few of them are expecting Armageddon in 2012. In fact, scholars say that Mayan communities call the end-of-the-world stories “gringo inventions.”