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In Our Time With Melvyn Bragg podcast: The Earth's Core

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Heart of Earth's inner core revealed

Scientists say they have gained new insight into what lies at the very centre of the Earth.
Research from China and the US suggests that the innermost core of our planet has another, distinct region at its centre.

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New ideas for how Earth core formed

Experiments on samples of iron and rock held at immense pressures have led to new ideas of how Earth's core formed.
Scientists from Stanford University have shown that iron metal will flow through rocks 1,000km beneath our feet.
Using sophisticated X-ray imaging, they watched molten metal moving through rocks, squeezed to huge pressures between the tips of pairs of diamonds.

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New insights solve 300-year-old problem: the dynamics of the Earth's core

Scientists at the University of Leeds have solved a 300-year-old riddle about which direction the centre of the Earth spins.
The Earth's inner core, made up of solid iron, 'superrotates' in an eastward direction - meaning it spins faster than the rest of the planet - while the outer core, comprising mainly molten iron, spins westwards at a slower pace.
Although Edmund Halley - who also discovered the famous comet - showed the westward-drifting motion of the Earth's geomagnetic field in 1692, it is the first time that scientists have been able to link the way the inner core spins to the behavior of the outer core. The planet behaves in this way because it is responding to the Earth's geomagnetic field.

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New idea tackles Earth core puzzle

Scientists have proposed a radical new model for the make-up of the Earth's core.
The study in the journal Scientific Reports may explain a longstanding puzzle about the most inaccessible part of our planet.
They suggest that data showing differences between the east and west hemispheres of the core are explained by the way iron atoms pack together.

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Earth's core far hotter than thought

New measurements suggest the Earth's inner core is far hotter than prior experiments suggested, putting it at 6,000C - as hot as the Sun's surface.
The solid iron core is actually crystalline, surrounded by liquid.
But the temperature at which that crystal can form had been a subject of long-running debate.
Experiments outlined in Science used X-rays to probe tiny samples of iron at extraordinary pressures to examine how the iron crystals form and melt.

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Geoneutrinos paint picture of deep-mantle processes.

A window on the deep Earth opened unexpectedly in 2011, when Japan's nuclear reactors were shut down after the Fukushima disaster. Before the closure, an underground particle detector called KamLAND based in Kamioka, Japan, was monitoring a torrent of neutrinos streaming from dozens of nearby nuclear reactors, seeking clues to the nature of these hard-to-catch subatomic particles. After those plants fell silent, KamLAND scientists could see more clearly a signal that had largely been obscured: a faint trickle of neutrinos produced inside the planet.
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Title: Earth Inner Core Periodic Motion due to Pressure Difference Induced by Tidal Acceleration
Authors: M. Wolf

The inner structure of the earth is still a topic of discussion. Seismic measurements showed a structure of solid, liquid, solid which describes the mantle, outer core and inner core with the inner core in the center. The analysis of waveform doublets suggests now that the inner core is out of center and even of faster rotation than the mantel and crust. From the sum of Buoyancy and Gravity on the earth inner core, the position energy is plotted and together with the tangential tidal acceleration, it is derived that Earth Inner Core cannot be in a center position without additional force. The Earth Core System is explained as Hydrodynamic Bearing. The Eccentricities out of nutation due to the effects from the sun and moon are calculated as an approximation.

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Title: Recent changes of the Earth's core derived from satellite observations of magnetic and gravity fields
Authors: Mioara Mandea, Isabelle Panet, Vincent Lesur, Olivier de Viron, Michel Diament, and Jean-Louis Le MouŽl

To understand the dynamics of the Earth's fluid, iron-rich outer core, only indirect observations are available. The Earths magnetic field, originating mainly within the core, and its temporal variations can be used to infer the fluid motion at the top of the core, on a decadal and subdecadal time-scale. Gravity variations resulting from changes in the mass distribution within the Earth may also occur on the same time-scales. Such variations include the signature of the flow inside the core, though they are largely dominated by the water cycle contributions. Our study is based on 8 y of high-resolution, high-accuracy magnetic and gravity satellite data, provided by the CHAMP and GRACE missions. From the newly derived geomagnetic models we have computed the core magnetic field, its temporal variations, and the core flow evolution. From the GRACE CNES/GRGS series of time variable geoid models, we have obtained interannual gravity models by using specifically designed postprocessing techniques. A correlation analysis between the magnetic and gravity series has demonstrated that the interannual changes in the second time derivative of the core magnetic field under a region from the Atlantic to Indian Ocean coincide in phase with changes in the gravity field. The order of magnitude of these changes and proposed correlation are plausible, compatible with a core origin; however, a complete theoretical model remains to be built. Our new results and their broad geophysical significance could be considered when planning new Earth observation space missions and devising more sophisticated Earth's interior models.

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Growth of Earth's core may hint at magnetic reversal

Lopsided growth of the Earth's core could explain why its magnetic field reverses direction every few thousand years. If it happened now, we would be exposed to solar winds capable of knocking out global communications and power grids.
One side of Earth's solid inner core grows slightly while the other half melts. Peter Olson and Renaud Deguen of Johns Hopkins University in Baltimore, Maryland, used numerical modelling to establish that the axis of Earth's magnetic field lies in the growing hemisphere - a finding that suggests shifts in the field are connected to growth of the inner core.

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