Schematic structure of the earth: inner and outer core, mantle and crust.
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The center of the earth is by no means still, but performs surprising rotational movements. The earth’s core may even rust, as seismic measurements and laboratory tests show.
What goes on in the Earth’s core, a sphere the size of Mars at the center of our planet, which continues to puzzle geoscientists. Today nobody doubts that the core of the earth is divided in two. It consists of a solid inner core about 2,400 kilometers in diameter overlaid by the almost equally thick liquid shell of the outer core. But what exactly happens in the center of our planet is in the dark. American and Chinese researchers have shed new light on the extremely hot, unimaginably high-pressure bowels of the Earth. In doing so, they made amazing discoveries.
Researchers have long suspected that the inner core appears to move independently of the rest of our planet. Among other things, this is indicated by precise measurements of the fluctuations in the length of the day. Every six years, the days get longer or shorter by about a tenth of a millisecond. About 30 years ago, researchers at Columbia University in New York attributed this change to the Earth’s inner core rotating slightly faster than the rest of the planet. They inferred this from changes in the travel time of earthquake waves traveling through the Earth’s core. Since then, however, the exact rate of movement of this Pluto-sized ball of iron and nickel has been debated.