Earth's core
What is at the centre of the Earth? 5,000 kilometres below the surface, the core lies between layers of rock and magma, as this videographic explains. VIDEOGRAPHIC
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00:00 What is at the center of the Earth?
00:09 Five thousand kilometers below the surface, the core lies between layers of rock and magma.
00:16 The core consists of a liquid outer core, primarily made of iron and nickel along with
00:21 other elements.
00:26 The solid inner core is also composed of an alloy of metals with approximately 90% iron
00:32 and 10% nickel.
00:34 The core's heat is instrumental in the formation of magma and large volcanic regions such as
00:40 Hawaii, Iceland, and Reunion Island.
00:43 The core has not always existed.
00:46 It was formed between 3 and 4 billion years after the Earth was created, when the planet
00:51 began to cool and a liquid core began to crystallize at its center.
00:57 The inner core is often called a planet within a planet.
01:01 It floats and moves freely within the liquid envelope of the outer core.
01:07 It's difficult to study how the core works.
01:10 What we do know is based on the analysis of seismic waves caused by earthquakes.
01:16 These waves pass through the center of the planet.
01:20 Scientists do not know for sure whether the core is spinning on itself and if so, in what
01:25 direction and at what speed.
01:29 We do know some of the effects of the core on the planet.
01:32 It creates the Earth's magnetic field caused by the iron in the core moving around.
01:38 This magnetic field helps many animals find their bearings and allows compasses to work.
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