National Geographic Today
Deadly asteroid impacts, reincarnated killer dinosaurs, alien invasions. Just when you thought Hollywood had thrown it all at us, a fresh, new, end-of-the-world scenario opens in theaters tomorrowthis time the action is 4,000 miles (6,400 kilometers) below our feet in The Core.
It seems the core of the Earth has stopped spinning and is no longer generating the planet's protective magnetic field. This triggers a cascade of diabolical events for man and beast. Birds can't navigate and fly erratically into buildings. People with pacemakers unexpectedly drop dead. Massive electrical storms destroy all electronic communication, and unfettered blasts of solar radiation fry the planet.
And unless an intrepid team of "terranauts" journey to the center and start it spinning again, everyone on the planet will be dead within a year.
It has all the makings of a blockbuster and it may not necessarily all be fantasy.
"I think of this movie as science faction more than science fiction," said Jon Amiel, director of The Core. "I think the audience will come out knowing a little more about the planet they're standing on."
The lead character in the film, himself a geophysicist, uses the anatomy of a peach to explain the different layers of the earththe skin represents an average 18 miles (30 kilometers) of the rock-hard crust, the flesh 1,700 miles (2,800 kilometers) of semi-molten mantle. The pit serves as the core4,350 miles (7,000 kilometers) across, about the size of Mars.
The core is subdivided into two layersinner and outer. The inner core is thought to be a solid ball of iron and nickel about two-thirds the size of the moon while the outer layer is a giant ocean of liquid iron and nickel.
Magnetic Field Shutdown
Eddies and currents in this metallic outer ocean produce Earth's magnetic field. "At least we believe that, though we don't understand exactly what the mechanism is," said Richard Terrile, a planetary astronomer at the Jet Propulsion Laboratory in Pasadena, California, and a science consultant for the film.
So can the magnetic field really shutdown?
"In fact it has happened many times in the Earth's history," says Terrile. "The Earth's magnetic field is not a stable solid thing like a bar magnetit actually changes, it moves directions, it goes up and down, and it actually reverses."
Don't throw away your compasses just yet. These shifts only occur every few hundred thousand years or so. But that's still enough to make the idea of a magnetic field shutdown at least plausible.
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