![]() Its liquid nature is revealed by the failure of shear-type seismic waves to penetrate the core. Explanation: The Earth is composed os several layers, see here for a summary of these layers. About one-third of Earth’s mass is contained in the core, most of which is liquid iron alloyed with nickel and some lighter, cosmically abundant components (e.g., sulfur, oxygen, and, controversially, even hydrogen). This is smaller and separate from what has long been held as Earth’s inner core. The inner core is a solid iron-nickel ball surrounded by a liquid outer core, also made of iron and nickel. ![]() “It’s like a planet within a planet that has its own rotation and its decoupled by this big ocean of molten iron,” Koper says.Ī recent unrelated study published in Nature Communications claims that there exists an innermost inner core of Earth that is a 400-mile-thick ball of mainly iron. Koper says that without the solid inner core, this field wouldn’t have the strength it does, and Earth’s surface would become bombarded with radiation and solar winds that would make the planet uninhabitable. This circulation generates bands of electrons that envelop the planet. The molten metal cools as it approaches Earth’s rocky mantle and sinks. The liquid outer core, which extends to 1,795 miles above the solid core, Koper says, produces a protective field of magnetic energy. The liquid outer core envelops the solid inner core. It’s made up of mostly iron and some nickel, along with a few other elements. While the idea of an inner core was first discovered in 1936 using seismic wave information, we’ve now measured the core about 4,300 miles across. ![]() We’ve known about some of the interplay between solid iron and liquid iron. Not all of the iron became solid, so some liquid iron could be trapped inside.” “It reached an equilibrium, and then it started to grow much more slowly. “A long time ago the inner core grew really fast,” Utah seismologist Keith Koper, who oversaw the study, says in a statement. You can also submit answers by post to: The Last Word, New Scientist, 25 Bedford Street, London WC2E 9ES.These changes come thanks to the growth of the inner core. Take a look at how temperature in the earth change with depth. The motion of the liquid outer core is what gives Earth its magnetic field. New Scientist Ltd retains total editorial control over the published content and reserves all rights to reuse question and answer material that has been submitted by readers in any medium or in any format. Due to the incredibly high temperatures and pressures near the center of the Earth, the outer core is liquid iron and nickel, while the inner core is solid. Please include a postal address, daytime telephone number and email address. We reserve the right to edit items for clarity and style. To answer this question – or ask a new one – email should be scientific enquiries about everyday phenomena, and both questions and answers should be concise. This current created an electric field that produced Earth’s own magnetic field. As the outer core metal rotated through the seed field, magnetic induction generated an electric current. Convection currents and rotation of the planet keep this circulating.Ī seed magnetic field, such as that of the sun, would have been required to get Earth’s field going. Around its solid inner core there is an outer core, a 2500-kilometre-thick layer of liquid iron and nickel. If you then heat it, they revert to random alignment.Įarth’s core is believed to act differently, like a dynamo. If you align the domains, by stroking the material with another magnet for instance, all these subdomains act in concert as one big domain, and now you have got a bar magnet. ![]() These are randomly aligned, so the net effect is no magnetism. In a hunk of ferromagnetic material like iron you have magnetic domains.
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