New Age mystics predict that December's turnover of the sacred Mayan calendar will bring death by flood, solar flares, or a catastrophic reversal of the Earth's magnetic field. Some even forecast that Earth will plunge into a gigantic black hole.
But don't bet the farm on it, say archaeologists.
This creative doom-saying stems from a calculation that archaeologist made in the 1980s, showing that the ancient Mayan timekeeping system was going to end, or cycle back to zero, for the first time since 3114 B.C.
The date for this turnover - December 21, 2012 - is now known to the apocalyptically minded as Y12. It raises the question: Could God's odometer be running out?
Archaeologists who have studied Mayan culture say the calendar won't end or go back to zero but extends for trillions of years into the future.
Either way, there was never an end-of-the-world prophecy. "It's misunderstanding on top of incomprehension on top of fooling yourself," said archaeologist Simon Martin of the University of Pennsylvania Museum of Archaeology and Anthropology.
Still, archaeologists are seizing this as a teachable moment when they can share what's known about the Maya and their remarkable achievements in astronomy, math and timekeeping.
These people of the Yucatan in southeastern Mexico and parts of Central America predicted lunar and solar eclipses and streamlined mathematics with the invention of zero while Europe was mired in the dark ages and struggling with cumbersome Roman numerals.
On May 5-6, the Penn Museum's annual Maya Weekend will focus on the calendar and coincide with the opening of an exhibit called Maya 2012: Lords of Time.
To understand the Mayan calendar, Martin said, it helps to realize their counting system was base 20 - meaning they had 20 numerals (including zero) rather than 10. While we mark time in weeks, they marked it in periods of 20 days. They gave a name to each day of these 20-day periods, just as we do our days of the week. They revered the number 13, and so they marked a "sacred round" that lasted 13 of these 20 day periods, or 260 days.
They also understood the year, which is rooted in astronomy, said Anthony Aveni, a professor of astronomy and anthropology at Colgate University and a speaker at the Penn Museum event.
Aveni wrote a book about the Mayan calendar called The End of Time: The Maya Mystery of 2012, which debunks the end-of-the-world hype and outlines what's known about the Maya, who thrived between 250 AD and 900 AD.
For decades, the Maya tracked the paths of the sun, moon, Venus and Mars until they could precisely predict eclipses and the positions of our neighboring planets. Pop culture books have attributed these feats to help from aliens, which Aveni thinks reflects a lack of respect for the intellectual powers of indigenous cultures.
Learning about Mayan astronomy was a revelation, he said. He had assumed Mayan astronomers were trying to understand the universe the same way he was. Did the Maya know that the planets and Earth orbited the sun? Did they realize the sun was a star in the Milky Way? He realized those weren't important questions to them.
The Maya understood that a solar year was a little longer than 365 days, he said, but they never added an extra day each leap year as we do. Instead, they let holidays drift around the calendar.
When it came to time, they were more concerned with cycles of 20 and 13, said Aveni. For longer-term calculations, they used what archaeologists call the "long count." It started with units of 360 days called Tuns. Twenty tuns made up a katoun, and 20 of those make a baktun.
Thirteen baktuns made up a creation period - 5,125 years and 133.7 days.
The 2012 date comes from the fact that the Maya set the current cycle to begin in 3114 B.C. Nobody is sure why this date was chosen. It predates Mayan civilization but may represent some round unit of Mayan time projected back from a date in their history, the way we count from the birth of Jesus.
On Dec. 21, or 23 depending on the calculation, the current cycle will end, and Mayan time will enter a new period, said archaeologist David Stuart from the University of Texas, another speaker this weekend at the Penn Museum.
He's found evidence that there are more digits to the left in the Mayan odometer, allowing orders-of-magnitude more years. "They were placing human time in this vast system with octillions of years in the past and octillions of years in the future," he said. "This is the biggest expression of time conceived by a human culture."
To Colgate's Aveni, the end-of-the-world hype comes from our projecting a Judeo-Christian worldview on Mayan timekeeping. "There's no evidence in Maya records that says much of anything about 2012, much less that it's the end of the world," he said.
But the Maya did appreciate milestones in time. The solar year and their sacred 260-day cycle lined up for them every 52 years, and there's some evidence they saw this as a reason to party.
They would have recognized the epoch-ending 2012 date as significant too, said Stuart. "It is an important date and it's very cosmic" even if their exact views remain a mystery.
at 215-854-4977 or firstname.lastname@example.org, or follow on Twitter @fayeflam. Read her blog at philly.com/evolution.