Getting to the Core Don't believe Jules Verne. The center of the Earth is not a nice place to visit, unless you like hanging out in a blast furnace. The outer core of the Earth, about two-thirds of the way to the center, is molten iron. With recent improvements in numerical techniques, density-functional theory had predicted iron's properties at low pressure with high accuracy, leading the researchers to believe that with supercomputing they could, in effect, reach 3,000 miles down into the inner core and pull out what they needed. Three crystal structures of iron.
Yellow lines show bonds between iron atoms.
Prevalent opinion before these calculations held that iron's crystal structure in the inner core was bcc. To the contrary, the calculations showed, bcc iron is unstable at high pressure and not likely to exist in the inner core. Hcp iron, however, gives a better fit with the seismic data. This led Stixrude and Cohen to try a computational experiment. The results, published in Science , offer the simplest, most convincing explanation yet put forward for the observed seismic data and have stirred new thinking about the inner core.