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The average magnetic field strength in Earth's outer core is estimated to be 2.5 millitesla, 50 times stronger than the magnetic field at the surface. [9] [10] As Earth's core cools, the liquid at the inner core boundary freezes, causing the solid inner core to grow at the expense of the outer core, at an estimated rate of 1 mm per year.
The transition between the inner core and outer core is located approximately 5,150 km (3,200 mi) beneath Earth's surface. Earth's inner core is the innermost geologic layer of the planet Earth . It is primarily a solid ball with a radius of about 1,220 km (760 mi), which is about 19% of Earth's radius [0.7% of volume] or 70% of the Moon 's radius.
The first detection of Earth's core occurred in 1906 by Richard Dixon Oldham upon discovery of the P-wave shadow zone; the liquid outer core. [9] By 1936 seismologists had determined the size of the overall core as well as the boundary between the fluid outer core and the solid inner core. [10]
A USC professor has confirmed what many scientists already believed: Rotation of the solid iron ball at Earth's center is slowing.
The findings open up new ways to investigate the inner core, according to lead author Thanh-Son Phạm. ANU also believes the innermost inner core hints at a major event in Earth's past that had a ...
Earth's inner core, a super-hot and super-compressed ball of iron smaller than the moon, helps generate the Earth's magnetic field and, by extension, the aurora borealis -- or Northern Lights.
Schematic of the Earth's inner core and outer core motion and the magnetic field it generates. The Earth's inner core is thought to be slowly growing as the liquid outer core at the boundary with the inner core cools and solidifies due to the gradual cooling of the Earth's interior (about 100 degrees Celsius per billion years). [49]
It is divided into a solid inner core, with a radius of 1220 km, and a liquid outer core. [55] The motion of the liquid in the outer core is driven by heat flow from the inner core, which is about 6,000 K (5,730 °C; 10,340 °F), to the core-mantle boundary, which is about 3,800 K (3,530 °C; 6,380 °F). [56]