The
Earth's inner core is the Earth's innermost part and according to
seismological studies, it has been believed to be primarily a
solid ball with a
radius of about 1220 kilometers, or 760 miles (about 70% of the
Moon's radius). However, with some recent studies, some geophysicists prefer to interpret the inner core
not as a solid, but as a plasma
behaving as a solid. It is believed to consist primarily of an
iron–
nickel alloy and to be approximately the same temperature as the surface of the
Sun: approximately 5700
K (5400 °C).