It's a common refrain that the ocean depths are the last great frontier of the Earth. Yet there's a place that's even more inhospitable to humans than the crushing depths of the sea: our planet's interior. It's made of iron, in some places it's 10,000 degrees F, and plenty of scientists devote their life's work to understanding it. But how exactly do you conduct research on an impenetrable, hostile environment like the Earth's core?

Back in the day, scientists and creative types alike used to believe that a whole different world lived below us. Jules Verne imagined a place ripe for adventure with dinosaurs and giant birds, while Edmond Halley thought the Earth was hollow with a couple concentric rings floating around in the middle. As cool …show more content…
Researchers like Maria Zuber, a geophysics professor at MIT, and Ishii have used evidence from space to support their conclusions about Earth. Iron meteorites collected after their fall to Earth are pretty solid clues that the element is plentiful in the Universe. Zuber says iron seems to be favored planetary building block. It's the heaviest element made during stellar fusion, so planets form with high concentrations of it.

Zuber and colleagues also have studied the insides of other planets to learn about Earth's core. While they can't get good seismic data from Mercury or Venus, researchers have found ways to make the comparison. In research published in the journal Science this year, Zuber and her colleagues at MIT examined Mercury's core by using the planet's magnetic field to their advantage.

"The fact that it [Mercury] has a magnetic field tells us that it's iron and that part of it is molten," Zuber says. Without at least a partially liquid core, convection wouldn't occur, making it impossible for a planet to form a magnetic field. These same processes happen inside the Earth, too. The energy released by the swirling liquid within our own planet's outer core allows Earth to create a self-sustaining, solar-wind-blocking shield. Without it, life on this planet wouldn't