Apocalyptic prophecies have spawned many science fiction movies. In the 2003 film The Core, the Earth loses its protective magnetic field when charged magma in the planet’s interior stops churning about. A mission to the center of the Earth is launched to get the magma spinning and save the planet. While these films are science fiction, some think these stories are set to come off of the screen and into reality in 2012.

To a rough approximation, the Earth’s magnetic field is like a bar magnet’s. It has a north pole and south pole, and field lines loop around its exterior, emerging from the north geomagnetic pole (Antarctic) and entering the geomagnetic south pole (Arctic). This field blankets the globe and extends out into space, and can be measured with a compass. The field’s “axis”, and consequently its poles, is not perfectly stable, and the poles drift by a few meters each year.

The Earth’s magnetic field exists thanks to liquid magma in the Earth’s core, which forms an ocean of iron ions carrying electric charge. The ions churn about inside the planet, and a net circular motion induces a magnetic field, much like a spinning electron does so in an atom. In both cases an electric current produces a magnetic field, which is known as Ampère’s Law.

The magnetic field that this generates moves continually. Larry Newitt, a researcher with the Geological Survey of Canada, periodicly runs an expedition through the Canadian arctic to find the exact location of the north magnetic pole.

The small pole shifts that occur gradually cause very little change to humans, other than a degree shift on compasses.

“Movement of the position of the magnetic poles — polar wander — is a well-documented process with little impact on life on scales sensible to us,” said Prof. Larry Brown, earth and atmospheric science.

On the Sun, magnetic poles shift entirely roughly every 11 years. The last polar shift on the sun occurred in 2001; thus, a solar pole shift is expected to occur in the year 2012. Some believe, however, that there will be a complete polar shift on the Earth as well.

Pole reversals have happened on Earth fairly often throughout history. According to NASA, each pole reversal throughout time was spaced between 50,000 and 50 million years apart, with an average of about 250,000 years between reversals.

The last pole reversal on earth occurred about 750,000 years ago, leading some to believe that the Earth is overdue for a pole reversal. When a pole reversal occurs, the strength of the Earth’s magnetic field decreases over time, and then grows in the reverse direction.

The entire process of pole reversal has taken hundreds of years or longer. Geological evidence shows that over the past several centuries, polar strength has been decreasing very gradually. However, the weakening of magnetic pole strength is not necessarily a sign of an upcoming pole shift. Over time, the strength of the magnetic field has often weakened, only to redouble without any flip occurring.

Even if the magnetic poles strength were to weaken more significantly or if the poles were to flip entirely, there is no evidence that it would have any lasting effect on human life.

“There is no evidence that these changes in magnetic pole strength have had any impact on life on earth,” Brown said, “despite the premise of the movie The Core.”

For some believers, however, the coming polar reversal of the Sun in 2012 is an omen of doom. The year 2012 coincides with the last date on the ancient Mayan calendar, which some believe to be a sign that Earth will meet its end.

These people predict that a polar reversal on Earth will coincide with that of the Sun. Due to the scheduled alignment of planets such as Saturn and Jupiter, along with the alignment of the Earth and the Sun’s north poles, they believe that an almost instant pole reversal will occur on Earth, resulting in natural catastrophes such as volcanic eruptions and earthquakes.

A second possible cause for the doomsday predicted by these believers is that a large imbalance caused by something like an enormous asteroid collision on Earth, will offset the magnetic poles enough to create a “polar wander.” They maintain that this would cause the Earth’s crust to shift rapidly, resulting in enormous and catastrophic climate change for its inhabitants.

But according to scientists, there is no factual basis for any of these claims.

“Rapid physical movements of the entire crust in polar regions is a suggestion with which I am not familiar,” Brown said. “However, it sounds like fantasy, not science. As for the 2012 ‘doomsday’ date, this is clearly a corrupt interpretation of Mayan calendrics.”

Prof. William White, earth and atmospheric science, agreed. “It sounds to me like a nut fringe idea that is completely without scientific basis,” White said. “On the long list of things we have to worry about over the next three years, this will certainly be at the very bottom of the list.”

Despite the lack of scientific backing, many people are still preparing for a possible apocalypse in 2012. Celebrity believers, according to several websites, include Mel Gibson and Lil’ Wayne. Many websites offer their explanations for how or why the Earth will end, with some even selling “survival” items from potable water to flashlights and gas masks.