The interior of the Earth is an inherently obscure and mysterious realm—so hidden and inaccessible from surficial observers that it’s long fired the imaginations of science-fiction writers as a redoubt of mythical and prehistoric beasts, wild landscapes, and lost civilizations. Scientific progress over the past century or so, however, has hugely illuminated the structures and processes of the planet’s innards, even though much remains speculative.
Recently, scientists made another leap forward in our conception of the very heart of the planet when they determined that previous estimates of its temperature were off by about 1,800 degrees Fahrenheit (about 1,000 degrees Celsius). The latest measurements, presented in an April 2013 issue of Science, suggest the inner core experiences a blistering 10,800 degrees F—roughly comparable to the mercury reading on the surface of the Sun. (Our star’s core temperature, however, is vastly hotter.)
French researchers working at the European Synchrotron Radiation Facility achieved the measurements by considering the melting point of iron—which, along with nickel, is thought to compose the alloy forming the planet’s center—when exposed to the extrapolated pressure at the margin of the Earth’s core, thought to be better than three million times that at sea level. After the iron samples were exposed to such dizzyingly intense conditions—courtesy of a tool known as a diamond anvil cell—they were scrutinized with X-rays to reveal how their crystal structures had responded.
The previous calculation of the core temperature, obtained in 1993 through iron analysis, had puzzled scientists because the difference between it and the temperature of the Earth’s mantle didn’t appear substantial enough to explain the planet’s magnetic field, which is believed to be induced by the combination of subterranean thermal motions and the planet’s rotation. The latest estimate is in better agreement with the model.
Refining our estimates for the Earth’s inner-core temperature gives us another of the pieces to the geological puzzle that is our home planet. Such breakthroughs help scientists and managers, including those with Environmental Data Resources, better understand the large-scale physical processes that dominate our existence.
To achieve some context for the new findings, let’s explore a little basic background on the Earth’s interior structure. That inner core of iron and nickel, some 700 to 900 miles across, is surrounded by an outer core made of basically the same material but in molten form. Above the outer core is the vast mantle, which—because of its extent across the middle and upper portions of the planet—accounts for the majority of the Earth’s volume. The mantle is divided into three sections. The innermost is the mesosphere, perhaps 1,600 miles deep, which is believed to consist of solid rock. The middle spectrum is the asthenosphere, several dozens of miles of plastic, mobile rock—movements within which are thought to explain plate-tectonic dynamics. Above the asthenosphere is the lithosphere, which includes the shallowest layers of the mantle as well as the lower portions of the Earth’s crust—its outermost “skin.” Both the lithosphere and the crust are primarily solid rock. The crust is thickest beneath continents, and far shallower beneath ocean basins.
So spare a moment to consider, up here on the (usually) pleasant crust of the planet, the infernal conditions down in the core—and those geological mysteries still yet to be uncovered.
Tom Grant is an environmental scientist and works building up Environmental Data Resources. He enjoys sharing his research on various environmental and business blogs.