Term
Outer core
Earth's liquid metallic layer, mainly iron with nickel and lighter elements, between about 2,890 and 5,150 km depth. It does not transmit shear waves.
What to look for
Swarm satellite observations constrain Earth's magnetic field. Its main source is the moving, conducting liquid outer core, not a permanent bar magnet; the solid inner core and the core's temperature are inferred from other evidence too.
Related labs
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