But could humankind really meet its end in 2012—drowned in apocalyptic floods, walloped by a secret planet, seared by an angry sun, or thrown overboard by speeding continents?

And did the ancient Maya—whose empire peaked between A.D. 250 and 900 in what is now Mexico and Central America—really predict the end of the world in 2012?

At least one aspect of the 2012, end-of-the-world hype is, for some people, all too real: the fear.

NASA's Ask an Astrobiologist Web site, for example, has received thousands of questions regarding the 2012 doomsday predictions—some of them disturbing, according to David Morrison, senior scientist with the NASA Astrobiology Institute.

"A lot of [the submitters] are people who are genuinely frightened," Morrison said.

"I've had two teenagers who were considering killing themselves, because they didn't want to be around when the world ends," he said. "Two women in the last two weeks said they were contemplating killing their children and themselves so they wouldn't have to suffer through the end of the world."

(Related gallery: "Apocalypse Pictures—Ten Failed Doomsday Prophecies.")

Fortunately, with the help of scientists like Morrison, most of the predicted 2012 cataclysms are easily explained away.

2012 MYTH 1
Maya Predicted End of the World in 2012

The Maya calendar doesn't end in 2012, as some have said, and the ancients never viewed that year as the time of the end of the world, archaeologists say.

But December 21, 2012, (give or take a day) was nonetheless momentous to the Maya.

"It's the time when the largest grand cycle in the Mayan calendar—1,872,000 days or 5,125.37 years—overturns and a new cycle begins," said Anthony Aveni, a Maya expert and archaeoastronomer at Colgate University in Hamilton, New York.

The Maya kept time on a scale few other cultures have considered.

During the empire's heyday, the Maya invented the Long Count—a lengthy circular calendar that "transplanted the roots of Maya culture all the way back to creation itself," Aveni said.

During the 2012 winter solstice, time runs out on the current era of the Long Count calendar, which began at what the Maya saw as the dawn of the last creation period: August 11, 3114 B.C. The Maya wrote that date, which preceded their civilization by thousands of years, as Day Zero, or 13.0.0.0.0.

In December 2012 the lengthy era ends and the complicated, cyclical calendar will roll over again to Day Zero, beginning another enormous cycle.

"The idea is that time gets renewed, that the world gets renewed all over again—often after a period of stress—the same way we renew time on New Year's Day or even on Monday morning," said Aveni, author of The End of Time: The Maya Mystery of 2012.

2012 MYTH 2
Breakaway Continents Will Destroy Civilization

In some 2012 doomsday prophecies, the Earth becomes a deathtrap as it undergoes a "pole shift."

The planet's crust and mantle will suddenly shift, spinning around Earth's liquid-iron outer core like an orange's peel spinning around its fleshy fruit. (See what Einstein had to say about pole shifts.)

2012, the movie, envisions a Maya-predicted pole shift, triggered by an extreme gravitational pull on the planet—courtesy of a rare "galactic alignment"—and by massive solar radiation destabilizing the inner Earth by heating it.

Breakaway oceans and continents dump cities into the sea, thrust palm trees to the poles, and spawn earthquakes, tsunamis, volcanic eruptions, and other disasters. (Interactive: pole shift theories illustrated.)

Scientists dismiss such drastic scenarios, but some researchers have speculated that a subtler shift could occur—for example, if the distribution of mass on or inside the planet changed radically, due to, say, the melting of ice caps.

Princeton University geologist Adam Maloof has extensively studied pole shifts, and tackles this 2012 myth in 2012: Countdown to Armageddon, a National Geographic Channel documentary airing Sunday, November 8. (The National Geographic Society owns National Geographic News and part-owns the National Geographic Channel.)

Maloof says magnetic evidence in rocks confirm that continents have undergone such drastic rearrangement, but the process took millions of years—slow enough that humanity wouldn't have felt the motion (quick guide to plate tectonics).

2012 MYTH 3
Galactic Alignment Spells Doom

Some sky-watchers believe 2012 will close with a "galactic alignment," which will occur for the first time in 26,000 years (for example, see the Web site Alignment 2012).

In this scenario, the path of the sun in the sky would appear to cross through what, from Earth, looks to be the midpoint of our galaxy, the Milky Way, which in good viewing conditions appears as a cloudy stripe across the night sky.

Some fear that the lineup will somehow expose Earth to powerful unknown galactic forces that will hasten its doom—perhaps through a "pole shift" (see above) or the stirring of the supermassive black hole at our galaxy's heart.

Others see the purported event in a positive light, as heralding the dawn of a new era in human consciousness.

NASA's Morrison has a different view.

"There is no 'galactic alignment' in 2012," he said, "or at least nothing out of the ordinary."

He explained that a type of "alignment" occurs during every winter solstice, when the sun, as seen from Earth, appears in the sky near what looks to be the midpoint of the Milky Way.

Horoscope writers may be excited by alignments, Morrison said. But "the reality is that alignments are of no interest to science. They mean nothing," he said. They create no changes in gravitational pull, solar radiation, planetary orbits, or anything else that would impact life on Earth.

The speculation over alignments isn't surprising, though, he said.

"Ordinary astronomical phenomena are imbued with a sense of threat by people who already think the world is going to end."

Regarding galactic alignments, University of Texas Maya expert David Stuart writes on his blog that "no ancient Maya text or artwork makes reference to anything of the kind."

Even so, the end date of the current Long Count cycle—winter solstice 2012—may be evidence of Maya astronomical skill, said Aveni, the archaeoastronomer.

"I don't rule out the likelihood that astronomy played a role" in the selection of 2012 as the cycle's terminus, he said.

Maya astronomers built observatories and, by observing the night skies and using mathematics, learned to accurately predict eclipses and other celestial phenomena. Aveni notes that the start date of the current cycle was likely tied to a solar zenith passage, when the sun crosses directly overhead, and its terminal date will fall on a December solstice, perhaps by design.

(Take a Maya Empire quiz.)

2012 MYTH 4
Planet X Is on a Collision Course With Earth

Some say it's out there: a mysterious Planet X, aka Nibiru, on a collision course with Earth—or at least a disruptive flyby.

A direct hit would obliterate Earth, it's said. Even a near miss, some fear, could shower Earth with deadly asteroid impacts hurled our way by the planet's gravitational wake.

Could such an unknown planet really be headed our way in 2012, even just a little bit?

Well, no.

"There is no object out there," NASA astrobiologist Morrison said. "That's probably the most straightforward thing to say."

The origins of this theory actually predate widespread interest in 2012. Popularized in part by a woman who claims to receive messages from extraterrestrials, the Nibiru doomsday was originally predicted for 2003.

"If there were a planet or a brown dwarf or whatever that was going to be in the inner solar system three years from now, astronomers would have been studying it for the past decade and it would be visible to the naked eye by now," Morrison said.

"It's not there."

2012 MYTH 5
Solar Storms to Savage Earth

In some 2012 disaster scenarios, our own sun is the enemy.

Our friendly neighborhood star, it's rumored, will produce lethal eruptions of solar flares, turning up the heat on Earthlings.

Solar activity waxes and wanes according to approximately 11-year cycles. Big flares can indeed damage communications and other Earthly systems, but scientists have no indications the sun, at least in the short term, will unleash storms strong enough to fry the planet.

"As it turns out the sun isn't on schedule anyway," NASA astronomer Morrison said. "We expect that this cycle probably won't peak in 2012 but a year or two later." (See "Sun Oddly Quiet—Hints at Next 'Little Ice Age'?")

2012 MYTH 6
Maya Had Clear Predictions for 2012

If the Maya didn't expect the end of time in 2012, what exactly did they predict for that year?

Many scholars who've pored over the scattered evidence on Maya monuments say the empire didn't leave a clear record predicting that anything specific would happen in 2012.

The Maya did pass down a graphic—though undated—end-of-the-world scenario, described on the final page of a circa-1100 text known as the Dresden Codex. The document describes a world destroyed by flood, a scenario imagined in many cultures and probably experienced, on a less apocalyptic scale, by ancient peoples (more on the Dresden Codex).

Aveni, the archaeoastronomer, said the scenario is not meant to be read literally—but as a lesson about human behavior.

He likens the cycles to our own New Year period, when the closing of an era is accompanied by frenetic activities and stress, followed by a rebirth period, when many people take stock and resolve to begin living better.

In fact, Aveni says, the Maya weren't much for predictions.

"The farther back you can plant your roots in deep time the better argument you can make that you're legit," Aveni said. "And I think that's why these Maya rulers were using Long Count time.

"It's not about a fixed prediction about what's going to happen."

ON TV 2012: Countdown to Armageddon airs Sunday, November 15, at 7 p.m. ET on the National Geographic Channel. Preview >>