Inside the belly of planet Earth, a giant solid ball of metal is surrounded by a swooshing layer of liquid iron and nickel, making up the two innermost stages of Earth’s geological layers.

The iron isn't pure—scientists believe it contains sulfur and nickel, plus smaller amounts ... Above the inner core is the outer core, a shell of liquid iron. This layer is cooler but still ...

It is spherical and solid and made up of iron and nickel. Its temperatures can reach 5500°C. Outer core The outer core is the layer surrounding the inner core. It is made of liquid iron.

They combined iron, nickel, and zirconium ... particularly the 77 Kelvin threshold at which liquid nitrogen can be used to ...